disease profile of crops in usm, kabacan, cotabato

ISBN 971-8676-18-X
DISEASE PROFILE OF CROPS
IN USM, KABACAN, COTABATO
A practical guide to diagnosing and
controlling common field diseases
2nd Edition
NAOMI G TANGONAN
JASMIN A PECHO
ELAINE GENEVIVE G BUTARDO
Published by the Plant Pathology Research Laboratory,
Crops Research Division, University of Southern
Mindanao Agricultural Research Center (USMARC),
University of Southern Mindanao
Kabacan, Cotabato, Philippines
2008
Suggested citation
Tangonan NG, Pecho JA, & Butardo EGG. 2008. Disease profile of crops in USM,
Kabacan, Cotabato: a practical guide to diagnosing and controlling common field
diseases. University of Southern Mindanao Agricultural Research Center (USMARC),
USM, Kabacan, Cotabato, Philippines, 50pp
ISBN 971-8676-18-X
2nd Edition & 1st Printing
Portions of this brochure maybe reproduced as long as acknowledgment of source
is attributed to the authors and the USM Agricultural Research Center (USMARC),
University of Southern Mindanao, Kabacan, Cotabato, Philippines.
Foreword
This brochure is the authors’
second attempt to put under one cover
a pictorial listing of the symptoms and signs
of common diseases of agricultural crops
grown or observed in the field and
experimental areas of USM
(with emphasis on fungal diseases).
New additions are aspects on disease control
or disease management.
The approach we adopted here
is to be able to help the beginner
or amateur plant doctor or
crop protectionist familiarize
her/himself with the basics
of disease diagnosis.
After all, no smart decision
or intervention on disease control
or management may be
devised without first
identifying or diagnosing
the cause and nature
(etiology) of the plant disease
based on symptoms and signs.
The authors welcome
your feedbacks, suggestions,
and comments.
Feel free to contact
them at the PPRL-USMARC, USM
or at telephone number
(064)-248-2610,
or mobile #s 0928-320-7548 (NGT),
0919-275-8671 (JAP), and
0928-264-6499 (EGGB).
Email: ngtangonan@gmail.com Acknowledgments
We express
our special thanks
and appreciation to the late
Dr Hersie C Nicor,
former director of the
University of Southern Mindanao
Agricultural Research Center (USMARC),
and the USM-based Cotabato Agriculture
Resources Research and Development
Consortium (CARRDEC), its current
Director Dr Elizabeth D Malacad,
for their full support
to this project.
Ms Jo-an P Pandoy
for editorial assistance.
Above all,
to God be the glory!
ii
Contents
Part I Symptoms of diseases on
Abaca 1
Alugbati 1
Ampalaya 2
Avocado 2
Balagay/Winged Bean 2
Banana 3
Cacao 4
Citrus (Calamansi, Pomelo) 4, 5
Cassava 5
Coconut 6
Coffee 6
Corn 6, 7, 8
Durian 9, 10
Eggplant 11
Gabi 11
Green Onion 12
Holy Basil 12
Jackfruit 13
Jatropha 13, 14
Kangkong 15
Langkawas 15
Lanzones 15
Lemon Grass 16
Mango 16
Mangosteen 17
Mungbean 17, 18
Oil palm 19
Okra 20
Orchid/Pakpak lawin 20
Papaya 21
Patola 22
Peanut 22, 23
Pechay 24
Pigeon Pea 24
Pineapple 24, 25
Rambutan 25
Rice 26
Rubber 27, 28, 29
Salago 30
Saluyot 30
iii
Sorghum 30
Squash 31
Sweet Pepper 31
Sweetpotato 31
Tarragon 32
Tomato 32
Ubi 33
Upo 33
Yam 33
Part II Pathogens of plant diseases
Algal pathogen
Cephaleuros virescens 34
Bacterial pathogens
Pectobacterium (Erwinia) chrysanthemi 38
Xanthomonas campestris pv oryzae (Ishi) Dye 42
Fungal pathogens
Alternaria solani 34
Cercospora abelmoschi 34
C. arachidicola 34
C. canescens 34
C. capsici 34
C. citrullina 34
C. manihotis 35
C. melongena 35
C. oryzae 35
Choanephora cucubitarum 35
Colletotrichum phomoides 35
C. gloeosporioides 35
Cordana musae 35
Corticium salmonicolor 35
Corynespora cassiicola 35
Curvularia inaequalis 35
C. lunata 36
Fusarium moniliforme 36
F. oxysporum 36
Helminthoporium sp. 36
H. heveae 36
H. oryzae 36
H. papayae 36
H. torulosum 36
iv
H. turcicum 37
Hemileia vastatrix 37
Lasiodiplodia theobromae 37
Macrophoma sp 37
Mycosphaerella fijiensis 37
Oidium heveae 37
Peronosclerospora philippinensis 38
Pestalotia palmarum 38
Phakopsora pachyrhizi 38
Phellinus noxious 38
Phomopsis ipomeae batatas 38
Phytophthora colocasiae 39
P. infestans 39
P.palmivora 39
P. parasitica 39
Pseudoperonospora cubensis 39
Puccinia arachidis 39
P. polysora 40
P. sorghi 40
Pyricularia grisea 40
Rhizoctonia oryzae 40
R. solani 40
Rigidoporus lignosus 41
Sclerotium rolfsii 41
Sphaceloma/Elsinoe mangifera 41
Theilaviopsis paradoxa 41
Ustilaginoidea virens 42
Nematode
Rotylenchulus sp 42
Virus diseases
Chlorotic streak of lemon grass 16
Leaf curl mosaic of papaya 21
Mangosteen mottle 17
Papaya ringspot 21
Part III How to diagnose disease of agricultural crops:
a simplified approach 43
Part IV Disease management / Control measures 45
References 47
Part I - Symptoms of plant diseases
ABACA (Musa textilis Nee)
Leaf blight of abaca caused by
Rhizoctonia solani Kuhn. Note
greenish-grey to white brown
margin, watersoaked spots that
spread rapidly to the leaves. In
severe cases sclerotial bodies
may be seen.
Abaca mosaic caused by a
virus. It is characterized by
alternating yellow and green
portions on the entire leaf
area.
Abaca leaf spot caused by Deightoniella
torulosa Ell. (Helminthosporium torulosum
Ashby.) Its initial symptoms are tiny dot-like
black spots, which when severe coalesce
and become big spots and manifest a blightlike appearance. As the disease progresses,
spots turn brown to almost black in advanced
stages.
Abaca bunchy top caused by the
banana bunchy top virus (BBTV).
It is characterized by yellowing
and curling of leaf blades. In
severe cases, infected plants
become stunted and clustering of
leaves will be noted.
Eyespot of abaca caused by Fusarium moniliforme Sheldon. Its initial
symptoms, are small black spots covered with yellow halos that later turn to
brown and form eye- like spot appearance.
ALUGBATI (Basella rubra L.)
Leafspot of alugbati (Ceylon spinach) caused
by Cercospora sp. Note irregular and round
or spherical straw-colored necrotic spots
Leafblight of alugbati caused
by Rhizoctonia solani
Kuhn. It is characterized
by enlarged, irregular,
brown watersoaked spots
with white mycelial growth
on the advancing portion of
the lesion.
AMPALAYA (Momordica charantia L.)
Ampalaya leafspots caused by Cercospora citrullina Cke. appear circular to irregular brown with yellow halo on
affected portions of the leaves.
AVOCADO (Persea americana Mill.)
BALAGAY/WINGED BEAN (Psophocarpus tetragonolobus (L.) DC)
Orange galls on leaves and fruits of balagay or winnged bean caused by Synchytrium psophocarpi DC.
BANANA (Musa sapientum L.)
Sigatoka disease caused by Pseudocercospora fijiensis Morelet
Zimm.(Mycosphaerella fijiensis Morelet) This disease causes dark
spots that eventually enlarge and coalesce, causing much of the leaf
area to turn yellow and brown. As the spots further increase in size, they
become dark brown surrounded by a yellow hypersensitive reaction that
separate spots from the normal green tissue.
Banana bunchy top virus (BBTV) disease. The symptoms may appear
at any stage of banana plant growth. The leaves become bunched
together towards the apex and a rosette is formed. Emerging leaves are
progressively shorter, narrower, stiff or crisp and papery to the touch, and
more erect than normal. The irregular, nodular, dark green dot-dash lines
or streaks appear running down the leaf stalk between the leaf blade and
pseudostem.
Leafspots of banana caused by Cordana
musae Hoehn. appear on mature leaves.
Small, irregular brown spots with yellow
halo and dark-brown to black centers
Banana speckle disease caused by
Cloridium musae Sta. showing scattered,
small black spots on leaf surface.
Leafspot caused by Cordana musae
Hoehn. Irregular lesions that vary in
size showing necrosis or browning of
leaf tissues affected.
Black spots on fruits caused by Macrophoma
musae Berk. & Vogl. or Sooty mold caused by
Cladosporium cladosporioides.
CACAO (Theobroma cacao L.)
Black pod rot of cacao caused by Phytophthora palmivora
Butler. Infected or wilted cherelles are caused by Colletotrichum
gloeosporioides Penz.
Leafspot of cacao caused by Pestalotia
palmarum Cke. appear as irregular,
round, brown spots that in time,
coalesce to develop larger lesions that
may result to death of the entire leaves
or even seedlings.
Leafspot caused by Colletotrichum gloeosporioides Penz.
Symptoms are small brown spots, irregular in shape with
yellow advancing portion around the lesion. Eventually, the
spots coalesce and form larger spots that sometimes cause
the leaves to deform. Severe infection may lead to drying
up of the leaves or death of seedling.
CALAMANSI (Citrus madurensis Lour.)
Scab of calamansi and King Mandarin caused by Elsinoe
fawcetti Bit. & Jen. (Sphaceloma fawcetti Jen.). The raised
surface of the fruits become rough with a light brown color
causing malformation and poor fruit quality.
Brown leafspots are scattered all over the surface of the
leaves. In advanced stages, the symptoms may spread to
the twigs and can cause the death of affected branches as
well as the death of the grafted seedlings. The pathogen id
Fusarium solani Appel & Wr.
Leafspot of citrus caused by Colletotrichum
gloeosporioides Penz. The spots are circular to
irregular and appear as light brown with a dark
brown halo.
Powdery
mildew
of
citrus caused by Oidium
tingitanium Carter.
POMELO (Citrus grandis L.)
Twig blight of pummelo caused by Fusarium
moniliforme Sheldon. It is characterized by yellowing
of leaves and discoloration of the vascular tissues
resulting to death of the affected twigs.
Pink disease of pummelo caused by
Corticium salmonicolor B. & Br.
Leaf symptoms of a suspected virus disease showing irregular
light green to yellow areas alternating with normal green areas
distributed in varying intensities and patterns without any
reference to veins.
Sooty molds caused by Capnodium citri
Berk. & Desm.
Citrus fruit from a virus infected tree.
CASSAVA (Manihot esculenta Crantz)
Leaf spot of cassava caused by Cercospora manihotis Henn. Note ring-like appearance on the leaf with yellow or
straw-colored centers. The lesions start by a discoloration of the leaf tissues.
COCONUT (Cocos nucifera L.)
Gray spot or leaf blight of coconut caused by Pestalotia palmarum Cke. The disease starts near
the midrib and distal ends, brown longitudinal lesions that can cover the entire leaf surface.
Leaf blackening or sooty mols caused by Caprodium footie Berk. & Desm. Commonly associated with coconut
mealybugs (Nipaecoccus nipae)
COFFEE (Coffea arabica L.)
Coffee rust underneath leaf
Sooty mold of coffee leaves
Coffee leaf rusts are circular yellow to orange spots on the affected leaves. Later, the spots become bigger
and produce dust-like particles on the under-surface of the leaves. The causal pathogen is Hemeleia vastatrix
B. & Br.
CORN (Zea mays L.)
Leaf blight of corn is caused by Rhizoctonia
solani Kuhn.
Downy mildew of corn caused by Peronosclerospora
philippinensis (Weston) Shaw continues to be the most
destructive corn disease in the Philippines. It affects the yield
potential and agronomic characteristics of corn.
Corn leaf rusts are
reddish-brown colored
pustules that erupt
releasing spores on both
sides of the leaf surface.
Puccinia sorghi Schw. and
P. polysora Underw. are
the pathogens that cause
the disease.
Leafblight of corn caused by
Curvularia inaequalis Boedj
Sheath blight of corn is caused by Rhizoctonia solani Kuhn.
On stems, the map-like appearance are at first ovoid and
greenish-grey, later becoming grayish-white with brown
margin. Spots are usually first observed at the soil line.
Sclerotial bodies are formed on the affected surface.
Corn ear rot caused by Fusarium moniliforme Sheldon produces
white-to-pink or salmon-colored moldy or white cottony growth on
surface of infected kernels
Corn leaf blight
Northern leaf blight of corn caused by
Helminthosporium turcicum Pass. It is
characterized by long, elliptical, grayishgreen or tan colored lesions on the
leaves.
Symptoms infected with
Fusarium stalk rot caused
by Fusarium solani. It
appeared as white mycelium
of the stalk, cross-section
showed shredding of the
pith tissues starts at the
nodes.
Stalks infected with the Gibberela
fungus have characteristics of pink to
reddish discoloration of the pith and
vascular strands. Rotting commonly
affects the roots, crown, and lower
internodes. The breakdown and
shredding of pith tissues starts at the
nodes.
Bacterial leaf stripe caused by Pseudomonas
rubrilineans, syn. P. avenae, Acidvorax avenae
subsp. Avenae. Lesions expand along veins,
producing a conspicuous striping, mainly in the
youngest leaves. Stripes later dry and brown, often
with shredding of the infected leaf tissue. Severe
damage of the top leaves results in tassel rotting,
when dead leaves enclose the tassel.
Corn smut caused by Ustilago maydis Corda.
Note powdery black mass of thick-walled
teliospores on affected area.
DURIAN (Durio zibethinus Murr.)
On leaves, blight is characterized by a halo of light green tissue on leaves caused by Fusarium sp. and
Rhizoctonia solani Khun. Fruit discoloration resulting to rot is caused by P. palmivora.
Sooty molds of durian
Durian blight
Phytophthora palmivora causing fruit rot, leafblight,
and dieback diseases of durian. Symptoms appear as
watersoaked lesions with light brown center 3-5 days
after infection, expands rapidly, and can completely rot
an entire plant part. Patches appear on fruit surface
as moist and damp.
P. palmivora also causes stem canker and appears
as wet lesion with bark cracking, particularly on the
base of the main stem near the soil and sometimes
on some branches. Bark is discolored with exudate
of reddish brown, resinous substance that ooze out
from the surface of affected areas. Wood lesions
are often very irregular in shape but are often welldefined. Infection can weaken the tree causing
defoliation and death of the affected branch or
dieback of the whole tree.
Fruit rot of durian caused by Lasiodiplodia theobromae
(Pat.) Griff. & Maubl. produces grayish mycelium found
behind the advancing portion of the lesion.
Vascular streak dieback (VSD) of durian
caused by Oncobasidium theobromae
Talbot and Keane. Staining of vascular
bundles/vessels are evident followed by
leaf yellowing and defoliation.
Stem canker and dieback of durian trees due to Phytophthora palmivora Butler. Note various symptoms on affected
trunk.
10
EGGPLANT (Solanum melongena L.)
Fruit rot caused by Phytophthora parasitica
Dastur The disease starts at any portion of the
fruit. The lesions are dark-colored and sometimes
covered with mycelial growth of the pathogen.
Infected portions are soft and watersoaked. The
lesion grows rapidly on mature fruits.
Leaf spot of eggplant caused by Cercospora
melongena Welles can affect not only the leaves
but also the stem, appearing watersoaked,
irregularly shaped with advancing yellow halo,
and scab-like brown edges. Dead tissue may
tear away from the healthy tissue leaving holes
on affected leaves.
Leaf blight caused by Phomopsis (Diaporthe)
vexans Hartig & Gratz Starts on the leaf tip and
advances upward as it progresses. The lesion
becomes wider and appears yellowing on the
affected portion. Mycelial bodies may be present
at a closer look on dried infected potion of the
leaf.
Wilt of eggplant makes the leaves turn yellow.
Wilting first occurs at the terminal leaves, until
the whole plant dies. It is caused by Fusarium
oxysporum Schlecht.
GABI/TARO (Colocasia esculenta (L.) Schott
Leaf blight of taro/gabi caused by Phytophthora colocasiae Rac. showing watersoaked, dark brown
to black lesions of infected leaves. Virus-like symptom of gabi (below).
11
GREEN ONION (Allium cepa L.)
Sclerotium rolfsii Sacc. causing blight of green onion. The pathogen attacks the lower
parts of the plant, turns yellow brown, wilts, until the whole plant dies. Mycelial strands
and dirty white, brown fruiting bodies can be seen on the collar region or above ground
part of the plant.
HOLY BASIL (Ocimum sanctum L.)
Leaf spot of holy basil caused by
Curvularia lunata (Wakker) Boedj.
Spots appear as small, yellowish
brown, circular to oblong.
Leaf blight of basil caused by
Fusarium moniliforme Sheldon.
Lesions are large, irregularly
shaped, that lead to death and
browning of affected tissues.
Leafspot of basil caused by Cercospora sp.
12
Virus-infected holy basil plant
showing leaf curling symptom.
JACKFRUIT (Artocarpus heterophyllus Lmk.)
Dieback and bark rot of jackfruit caused by
Fusarium moniliforme Sheldon. It is characterized
by brown, watersoaked necrotic bark along the
trunk. White mycelial growth of the pathogen
can also be observed extending internally into
the cambium layer that as result, the affected
area turns yellow, dries up, and later death of the
whole tree occurs.
Fruit rot of jackfruit caused by Sclerotium rolfsii Sacc. Note whitish mycelia of the fungus on
the affected black portions
JATROPHA (Jatropha curcas L.)
Seedling blight/ damping off
caused by Choanephora sp.
Leafspot caused by Cercospora sp.
Anthracnose leafspot caused by
Colletotrichum gloeosporioides
Penz.
Leaf blight caused by Helminthosporium sp. and leafspot caused by Curvularia sp. (right)
Virus-infected leaves of Jatropha showing mottling, curling, and fan leaf symptoms.
13
Moldy rot Jatropha nuts.
Leafspot caused by Thielaviopsis (Chalara)
paradoxa (Dade) Moreau
Symptoms of diseases on jatropha caused by various fungal pathogens (Curvularia, Cercospora, and
Thielaviopsis).
14
KANGKONG/ SWAMP CABBAGE ( Ipomoeae aquatica Forsk.)
White rust of kangkong caused by Albugo ipomoeae aquatica Sani.
LANGKAWAS (Alpinia galanga L.)
Leafspot of turmeric caused by
Fusarium moniliforme Sheldon.
Small circular spot appear as
brown to light brown.
Rust of langkawas caused by
Uromyces sp.
Leaf blight of langkawas caused
by Macrophoma sp. The lesions
are elongated and enlarge rapidly
to cause complete yellowing
resulting to death of the leaves.
LANZONES (Lansium domesticum Jack)
Leaf blight caused by Fusarium moniliforme Sheldon. Early
symptoms are the presence of irregular brownish lesions which
enlarge and dry up. The infected leaves eventually withers and
falls. In favorable condition, presence of pinkish-white, hairy
growth on surface of the infected tissue were visible.
Scab on fruit.
Leaf blight of lanzones caused by Colletotrichum gloeosporioides Penz. with
watersoaked lesions, brown with yellow halos from the leaf tip and margins to the entire
leaf area.
15
LEMON GRASS (Cymbopogon citratus (DC) Stapf)
Virus disease of lemon grass showing lightly chlorotic
streak (light green to yellowish lines) and reddish to brown
dead tissues on the leaves (right).
Sudden death of lemon grass caused by
Sclerotium rolfsii Sacc. indicated by maplike
blight on the leaves and leaf sheaths and a white
mycelial growth with sclerotial bodies of the causal
pathogen on the base of the plant.
MANGO (Mangifera indica L.)
Scab disease caused by Sphaceloma/Elsinoe mangifera Bit. & Jen. on Carabao mango. Note the dry rot and
cracking effect of scab and also the incidence of anthracnose fruit rot on right photo.
Carabao mango fruits showing stem-end rot disease
caused by Lasiodiplodia theobromae (Pat.) Griff. &
Maubl. (note broader infection of dark brown rots at stem
ends).
Early and advanced symptoms of anthracnose caused
by Colletotrichum gloeosporioides carabao mango.
Pink disease caused by
Corticium salminocolor B. &
Br. attacks the trunks, twigs,
and branches on mango.
It may appear typically as
spider-like structure covering
the infected surface. It turns
thick, smooth, and pink in
color during rainy season.
16
Anthracnose on leaves caused by
Colletotrichum gleoesporioides.
MANGOSTEEN (Garcinia mangostana L.)
Leaf spot of mangosteen (Alternaria
sp.) occurs as small, dark necrotic
spots.
Seedling wilt of mangosteen predisposed by sun scalding.
When sectioned, brown to black color on the root system
of infected seedlings are apparent.
Virus-infected mangosteen tree showing mottling of
the leaves (alternate light and dark green areas color).
Symptoms characterized by mosaic, stunted growth
reduced leaf size, shortened internodes, and erect, stiff
leaves.
Virus disease of
mangosteen. Note
chlorosis and
reduced width size of
leaves.
MUNGBEAN/ STRING BEAN
(Phaseolus aureus Roxb./Vigna radiata (L.) Wilczek)
Leaf spots of mungbean are
irregular shapes with tan centers.
Lesions increase in size and
coalesce until the greater part of
the leaf infected. The disease is
caused by Cercospora canescens
Ell. & Mart.
Powdery mildew of beans caused by
Erysiphe polygoni DC.
Rust of string beans caused by
Phakopsora pachyrhizi.Syd.
The lesions are small, reddish
in color and surrounded by
yellowed leaf tissue.
Virus-infected string beans.
17
Samples of legumes showing symptoms of leafspots, blights, leaf curling, and insect damage.
18
OIL PALM (Elaeis guineensis Jacq.)
Anthracnose of oil palm
caused by Colletotrichum
gloeosporioides Penz.
Leafspot of oil palm caused by
Pestalotia palmarum Cke.
Rachis blight of oil palm caused by Thielaviopsis
(Chalara) paradoxa (Dade) Moreau
Leafblight of oil palm caused by
Curvularia lunata (Wak.) Boedj.
Leafspot of oil palm caused by Fusarium
moniliforme Sheldon.
Heart rot of oil palm caused by Pectobacterium chrysanthemi Burk.
Stem/ bud rot of oil palm caused by
Rhizoctonia solani Kuhn.
Basal trunk rot caused by Ganoderma lucidum Karst.
19
OKRA (Hibiscus esculentus L.)
Leaf spot or leaf mold (lower left) of okra caused by Cercospora abelmoschi Chupp & Sher. looks like a combination
of black and purplish, small spots on the upper surface of the leaves. Mycelia (grayish to black) or threadlike
structures of the causal pathogen can be seen on the undersurface of the leaf.
Severe moldy
rot on okra
showing entire
fruit covered with
fungal growth.
ORCHID / PAKPAK LAWIN (Asplinium nidus Linn.)
Leaf blight on
pakpak lawin.
20
Black spot of orchid.
PAPAYA (Carica papaya L.)
Leaf curl mosaic virus of
papaya showing irregular
reduction and malformation
of pale green leaves. In
advanced stage, plants
appear mottled, distorted,
wrinkled, and the edges curl
downward
Leafblight of
papaya caused by
Phytophthora
parasitica Dast.
Papaya ringspot virus-infected tree.
Crown rot of papaya
caused by Pectobacterium
carotovora subsp. atroseptica
(Van Hall) Dye . It is one of
the most widespread and
destructive diseases of
papaya that infects fruits,
leaves, petioles, and causes
wilting and rotting of the
growing point resulting to
decapitation and toppling over
the shoot.
Leafspot of
papaya caused by
Helminthosporium
papayae Sydow. It
is characterized by
a small brown with a
yellow halo lesion.
21
Virus-infected papaya
and fruit rot.
PATOLA (Luffa cylindrical Auct. NonRoem.)
Leaf blight and fruit rot on papaya.
PEANUT (Arachis hypogaea L.)
Wilted and stem rot of peanut showing severe infection of Sclerotium rolfsii
Sacc. and exhibit symptom of decline
22
Symptoms of early leafspot of
peanut (Cercospora arachidicola
Hori.) observed.
Peanut rust (Puccinia arachidis Speg.)
Symptoms of leafblight of peanut
(Fusariumn
oxyporum
Schlecht.)
observed.
Root rot of peanut caused by nematode, Rotylenchulus sp.
Leaf rust of peanut caused by Puccinia
arachidis Speg.
23
PECHAY (Brassica pekinensis (Lour.) Rup.)
Wilt of pechay caused
by Fusarium oxysporum
showing water-soaked
infected part (crown) and
whitish growth of causal
pathogen
PIGEON PEA/KADYOS (Cajanus cajan (L.) Huth.)
Leaf spot of pigeon pea caused by
Cercospora canescens Ell. & Mart.
appears as small brown, with a yellow
halo.
Leaf blight of pigeon pea starts from the leaf
margin and later spreads to the entire leaf.
PINEAPPLE (Ananas comosus (L.) Merr.)
Phytophthora heart rot
Wilt caused by Fusarium
Bacterial heart rot
Butt rot caused by Pectobacterium chrysanthemi
Nematode-infected
crown of pineapple.
24
Pineapple plants showing various degrees of root rot caused by Pythium spp.
RAMBUTAN (Nephelium lappaceum L.)
Pink disease caused by Corticium salmonicolor B. & Br.
attacks the trunks, twigs, and branches of rambutan.
The disease may appear typically as spider-like structure
covering the infected surface. It turns thick, smooth, and
pink in color during rainy season. The infected plant parts
dry-up.
Algal spot caused by Cephaleuros virescens attacking
the upper portion of leaves. The lesions forming more or
less circular spots on the leaf.
Leaf blight of rambutan caused by Colletotrichum
gloeosporioides Penz. infects the leaf margin and
eventually advances until brown colored lesion
developed.
Vascular streak dieback of rambutan caused by
Oncobasidium theobromae T. & K. Staining is evident
when the affected twigs are detached and cut up.
25
RICE (Oryza sativa L.)
Symptoms consist of brown,
dark, circular to oval spots that
vary in size. Spots on seedlings
may become numerous. It
caused by Helminthosporium
oryzae B. de Haan.
Bacterial leaf blight (Xanthomonas
campestris pv oryzae (Ishi.) Dye).
The first symptom of the disease
are water soaked lesions on the
edges of the leaf blades near the
leaf tip. The lesions expand and turn
yellowish and eventually become
grayish-white. In severe cases, it
leads to panicle blight.
Panicle blight appear at heading
during grain fill, small clusters of
panicles do not fill out, and turn
over because they are unfilled.
Leaf and shealth blight. The disease
caused by Rhizoctonia oryzae Ryker &
Gooch or R. solani Kuhn starts from the
basal leaf sheaths as water soaked spots
with light brown or straw-colored center
and reddish border. These lesions usually
develop just below the leaf collar as oval
to elliptical, green-gray spots
Dark brown to black spots are often large
enough to cover entire grain. Affected
grains may be poorly filled and chalky. It is
also caused by Helminthosporium oryzae
B. de Haan (Cochliobolus miyabeanus False smut. Spore balls are found in place of grain or around the grain
and reduce the quality of the produce. The spores are greenish on
Drechs.).
outside and yellow orange inside. Disease incidence maybe seen at
postflowering to ripening stage of the crop. It is caused by Ustilaginoidea
virens Tak.
Narrow brown leaf spot on leaves and upper
leaf sheaths include short, or long linear lesions
that become numerous as the plant approaches
maturity. It is caused by Cercospora oryzae
Miyake (Sphaerulina oryzina Hara).
26
Leaf blast caused by Pyricularia grisea (Cooke) Sacc. (P.
oryzae Cav). It can cause serious losses to susceptible
varieties. Depending on the part of the plant affected, the
disease is often called leaf blast, rotten neck, or panicle
blast. The center of the spot is usually gray and the margin
brown or reddish-brown.
IRPT rating scale used
in the assessment
of Rhizoctonia leaf
and sheath blight of
15 rices, 0 means of
infection.
RUBBER (Hevea brasiliensis (Muell.) Arg.
Bird’s eye spot caused by
Helminthosporium heveae
Petch.
Anthracnose leafspot and leafblight caused by Colletotrichum gloesporioides
Penz.
Powdery mildew caused by
Oidium heveae Stein.
Leaf and seedling blight and Leafblight caused by P. palmivora and
wilt caused by Fusarium Rhizoctonia. solani Khun.
oxysporum f. sp. vasinfectum
Snyd. & Hans.
Leafspot/Leaf fall caused by Corynespora cassiicola (Berk and Curt)
27
Seedling blight of rubber.
Powdery mildew of rubber.
Seedling blight caused by Phytophthora palmivora
Butler.
Knob-gall of rubber.
Black stripe, stem canker, and bark splitting due to
P. Palmivora.
Pink disease caused by Corticium salmonicolor B. & Br.
Knob gall and stem bleeding caused by Lasiodiplodia theobromae (Pat.) Griff. & Maubl.
28
White and brown rot diseases caused by Rigidoporus lignosus Imazeki and Phellinus noxious Cunn.
Root damage due to white and brown root rots caused by Rigidoporus lignosus and Phellinus noxius.
Leafspot and leafblight on rubber.
29
SALAGO (Wikstroemia lanceolata L.)
Stem and leaf blight of salago caused by
Rhizoctonia solani Kuhn, resulting to death of the
affected leaves and twigs.
SALUYOT / JUTE (Corchorus olitorius L.)
Leafspots caused by Cercospora
corchori Saw., Colletotrichum
sp., Curvularia sp., and
Helminthosporium sp
SORGHUM (Sorghum bicolor (L.) Moench.
Leaf and sheath blight of sorghum caused by Rhizoctonia solani Khun
first appear as small, purplish, long irregular spots. Cloudy and humid
conditions favor the pathogen to abundantly grow its mycelia that colonize
the sheath causing it to bend, dry, and die.
Rust of sorghum caused by
Puccinia sorghi Schw. or P.
pupurea Cke. showing small,
orange to brown spots on the
leaves. Spots coalesce forming
raised lesions filled with rust
uredospores.
Black/tar spot of sorghum caused by Phyllachora sorghi
v. Hoehnel.
Leaf spot of sorghum caused Curvularia sp.
30
SQUASH (Cucurbita maxima Dcne.)
Squash can be infected by viruses at any stage of growth. When
infected, the leaves turn yellow, and show abnormal growth.
Infected fruits reveal patterns of white blotches interspersed with
dark green spots that are raised into conspicuous blisters.
SWEET PEPPER (Capsicum annuum L.)
Fusarium oxysporum (Schlecht.) Snyder & Hansen causes wilt of
sweet pepper and infects the roots and vascular tissues (causing its
discoloration) leading to death of the plant.
Brown leaf spot caused by
Cercospora capsici Heald and
Wolf. It infects on surface of
the leaves with grayish centers
scattered all over the leaf area.
Spots are circular to irregular, enlarge
with age, the center becomes light brown
with dark margins. Later, the necrotic
tissues drop off leaving a shot-hole
effect. The disease is due to Cercospora
capsisi Heald & Wolf.
Bacterial fruit rot of sweet pepper
caused by Erwinia carotovora
(Jones) Bergy et al.
SWEETPOTATO (Ipomoea batatas (L. Lam.)
Gray leaf spot of sweet potato caused by Phomopsis ipomeae batatas Pun. (Phyllosticta batatas), is either
angular or circular with a brown halo and light brown necrotic lesion at the center where pycnidia or fruiting
bodies may be seen.
31
TARRAGON (Artemisia dracunculus L)
Stem blight of tarragon caused by Sclerotium rolfsii. Sclerotial bodies may be seen in severe cases (above).
Leaf curling of tarragon
caused by a virus.
TOMATO (Lycopersicon esculentum Mill.)
Leaf blight of tomato caused by Alternaria solani Jones. &
Grout (left).
Fruit rot of tomato caused by Phytophthora
infestans de Bary, it is characterized by
watersoaked brown lesions that later increase
in size until the whole fruit rots. Note cottony
mycelial growth (right).
Leaf blight of tomato caused by
Rhizoctonia solani.
32
Sclerotium rolfsii causing fruit
rot of tomato.
Fruit rot of tomato caused by
Colletotrichum phomoides
Chester.
UBI (Dioscorea alata L.)
Infected portion is clearly
defined, it spreads rapidly over
the leaf lamina, collapses, and
turns brown. It is caused by
Colletotrichum gloeoprioides.
UPO (Lagenaria leucantha (Duch.) Rusby)
Brown and circular specks lesions of upo,
the centers become light in color. The
pathogen is Colletotrichum lagenarium Ell.
& Halst.
Downy mildew symptoms appear angular
yellow on the leaves on the upper side and
purplish mildew on the lower side. The
causal pathogen is Pseudoperonospora
cubensis Rostow.
Typical symptom of mosaic virus disease of upo or
bottle gourd. The leaves have irregular pale green with
dark green spots scattered. In advanced stage, plants
appear mottled, distorted, wrinkled, and the edges curl,
downward.
Postharvest disease of upo caused by Fusarium
sp. Symptom starts from peduncle which later
advances as the disease progresses.
YAM (Dioscorea alata L.)
Leafblight of yam (ubi)
33
Part II - Signs (pathogens) of plant diseases
Alternaria solani Jones & Grout
Cercospora abelmoschi Chup & Sher
Cercospora capsici Heald & Wolf
34
Cephaleuros virescens Kunze
Cercospora
arachidicola Hori
Cercospora canescens Ell & Mart
Cercospora citrullina Cke
Cercospora manihotis Henn
Cercospora melongena Welles
Cercospora oryzae Miyake
Choanephora cucubitarum Thaxter
Colletotrichum phomoides Chester
Colletotrichum gloeosporioides Penz
Cordana musae Hoehn
Corticium salmonicolor B. & Br.
Curvularia inaequalis Boedj
Corynespora cassiicola (Berk& Curt) Wei
35
Fusarium moniliforme Sheldon
Curvularia lunata (Wakker) Boedj
Helminthosporium sp
Fusarium oxysporum (Schlecht) Snyder & Hansen
Helminthosporium oryzae B de Haan
Helminthosporium heveae Petch
Helminthosporium torulosum Ashby
Helminthosporium papayae Sydow
36
Helminthosporium turcicum Pass
Hemileia vastatrix B. & Br.
Lasiodiplodia theobromae (Pat) Griff & Maubl
Macrophoma sp
Mycosphaerella (Para/Pseudocercospora)
fijiensis Morelet
Oidium heveae Stein
37
Pectobacterium chrysanthemi Burk
Peronosclerospora philippinensis (Weston) Shaw
Pestalotia palmarum Cke
Phakopsora pachyrhizi Sydow
Phellinus noxious Cunn
Phomopsis ipomeae batatas Pun
38
Phytophthora colocasiae Rac
Phytophthora infestans de Bary
Phytophthora palmivora Butler
Phytophthora parasitica Dastur
Pseudoporonospora cubensis Rostow
Puccinia arachidis Speg
39
Puccinia polysora Underw
Puccinia sorghi Schw or P purpurea Cke
Pyricularia grisea (Cooke) Sacc (P oryzae Cav)
Puccinia sorghi Schw or P pupurea Cke
Rhizoctonia oryzae Ryker & Gooch or R solani Kuhn
Rhizoctonia solani Kuhn
40
Rigidoporus lignosus Imazeki
Sclerotium rolfsii Sacc
Sphaceloma/ Elsinoe mangifera Bit & Jen
Theilaviopsis (Chalara) paradoxa (Dade) Moreau
41
Ustilaginoidea virens Tak
Xanthomonas campestris pv oryzae (Ishi) Dye
Nematode
Rotylenchulus sp
42
Part III - How to diagnose diseases of
agricultural crops: a simplified approach
Diseases lower crop yields
Diseases attacking agricultural crops are constraints to bigger yields. Field and postharvest
diseases lower both the quality and quantity of all food crops, feed grains, and fibers.
Some examples of diseases that limit yields are downy mildew and stalk rot of corn, tungro,
blights and blast of rice, head molds of sorghum, rust of coffee, peanut, and soybean, virus
diseases of legumes and vegetables, and bunchy top of abaca, wilt and damping- off seedlings,
sigatoka leaf spot and moko wilt of banana, pod rot of cacao, root- knot galls of ramie, eggplant,
tomato, citrus, pink disease and black stripe of rubber.The list goes on…
Diagnosis through field symptoms
The most practical approach to diagnoses of crops is by means of their field symptoms. This
means taking a look at their appearance. Any apparent abnormality in the plant/plant part
(caused by disease- causing organism called pathogen) when compared to its healthy counter
part is a good starting point. This should not be confused, however, with certain disorders in
plants which may be due to nonliving factors or physiological deficiencies in soil nutrients (e.g.
lack of fertilizers such as NPK and/ or other elements).
Some common symptoms of diseases
Stunting A diseased crop may be stunted with stiff leaves and yellowish or dark color coupled
with an overgrowth of tiller of leaves, thus a bushy and dwarf appearance.
Wilting, Galling Soilborne microorganisms that attack the roots of crops enter and plug the
vascular tissues in the stem thereby causing wilt. This can differentiated from ordinary wilting
(caused by moisture- temperature stress) by the presence of brownish or dark color in the
tissues when the stem is cut across or lengthwise. Meanwhile, solanaceous crops are easy prey
to invasion of cysts or root- knot galls due nematodes and bacterial infection (Agrobacterium
tumefaciens is a common cause of crown gall).
Twisting, Wrinkling These symptoms are usually indicative of a virus disease. In some cases,
they lead to “ witches’ broom” with the leaves and shoots arising from a common point. Leaf
surfaces may develop depressions and protruded tissues or tumors and the damage aggravated
by insects. Overall size is greatly reduced.
Chlorosis, Necrosis Infection begins with the appearance of small chlorotic spots of lesions
on leaves, leaf sheaths, and stem. These may also be recognized as streaks, stripes, or blights
with irregular, water soaked, and enlarged map - like zonations. The loss of chlorophyll (green
color) creates a clear contrast with the healthy tissues.
43
For virus symptoms, mottling and mosaic patterns are evidenced by distinct borders alongside
darker shades on the affected part of the latter. Severe chlorosis may lead to necrosis or the
eventual death of tissues. At times this is characterized by what looks like a cottony or powdery
outgrowths as in mildews caused by fungi or by some rough encrustations as in rusts, smuts,
and scabs.
Soft and hard/dry rots Stored and transported fleshy and non fleshy fruits, vegetables, pods,
berries, nuts, and grains are favorite targets of postharvest microorganisms. Soft rots are
usually due to bacteria and characterized by a slimy feel and a strong foul odor, while hard and
dry rots are possibly due to fungi, oftentimes covered with dry spores with a distinct moldy or
mushroom-like odor.
Important Reminders
It must be borne in mind that many diseases caused by bacteria, fungi, nematodes, and viruses
may show similar symptoms. In such a case, further laboratory (microscopic) observation of the
physiological and cultural characteristics of the host pathogen are needed. Ideally, this will also
require that the organism be tested for pathogenicity or its ability to cause disease using Koch’s
Postulates or rules of pathogenicity.
44
Part IV- Disease management/Control measures
A combination of two or more methods or an integrated approach in disease management and
control is the most useful tool to combat diseases of crops. If the damage is limited to certain
parts of the crop (localized and has not spread) at its early stage and severity is not extensive,
the disease may be controlled. Similarly, if a population shows only an isolated and negligible
number of infected plants, control is recommended. One has the option to control or manage
diseases in many ways. Through any of the following methods done singly or a combination of
any two or all methods in an integrated approach, to wit:
Cultural (intercropping, proper plant density, weeding, off-barring, hilling-up, trap cropping,
irrigation, modify cropping practices). When a disease attacks the crop, the cropping pattern
used may be modified or altered by using an entirely different one. An example is crop rotation
– planting another crop in sequence. Say soybean after rice, peanut after corn, mungbean
after sorghum. The temporary absence of the main crop prevents the build- up of pathogens
that would otherwise be favored in the next cropping season. Intercropping or strip cropping- is
another strategy that can be done to prevent the spread of the pathogens. Intercrops, therefore,
act as trap crops preventing further spread of the disease.
Other cultural practices that may be done are: fallowing the field (temporary absence of any
crop), intermittent flooding or irrigation, weeding and cultivation, deep- plowing the soil to
expose the micro organisms under the sun, and burning all field trash or debris within and in
the immediate parameter of the area. Furthermore, applying the needed fertilizers will not easily
predispose the crops to diseases.
Mechanical (rouging, pruning, etc) A practical way of controlling diseases is by rouging or
removing diseased plants and pruning or cutting infected parts and burning them immediately.
Physical (solar radiation, smudging, light traps for pathogen-carrying insects)
Chemical (spraying, swabbing, drenching pesticides) - The judicious use of the appropriate
pesticide/s may be the last choice to be considered. Your local agrochemical dealer has
adequate supplies of pesticides for all types of crop diseases. Specific instructions on the
product label must be strictly followed in terms of how much quantity is needed and how to
apply the particular fungicide.
Organic-based formulations applied as sprays, swabs, or soil drench (fermented teas from
agriwastes of plants and plant parts like fruit peels, cobs, legume pods, bagasse, straw, or
animal wastes like earthworm vermicasts, manures, etc)
45
Use of biocontrol agents and biopesticides
• antagonists (nonpathogenic or nontarget microorganisms like bacteria, fungi, mild strain
viruses for cross protection, predators or friendly insects, etc).
• botanicals (plants with pesticidal properties: fungicidal, bactericidal, nematicidal, insecticidal,
viricidal)
Use of resistant varieties or cultivars - When and if resistant varieties are available these are
highly recommended. In addition, they must be certified and disease- free planting materials.
However, it must be pointed out that proper field management is still necessary to ensure
maximum yields.
46
References
Alejandro FR, Tangonan NG, Malacad WB, Escalante WB, & Miral PR. 1990. Thirteen
outstanding sorghums developed at USMARC-USM, Kabacan, Cotabato. USM CA Res.
Journal 1:223-228
Ayob JT & Tangonan NG. 2000. Identification and chemical control of two pathogens of salago
(Wikstroemia lanceolata L.). USM CA Res Journal 11 (1): 82-91
Balmores LM, Jover EM, & Tangonan NG. 1992. Etiology of rubber stem bleeding at USMARC.
The USM CA Res Journal 3: 53-57
Cahatian PO & Tangonan NG. 2009. Pests and Diseases of Jatropha and their Management,
CHED-funded, USM, Kabacan, Cotabato ISBN 978-971-8676-28-8, 67 pp Brochure
Dela Torre AC Jr & Tangonan NG. 2008. Efficacy of Jatropha extracts against Cordana musae
causing leafspot of Cardava banana. USM R & D Journal 16 (1):89-97
Godoy JC & Tangonan NG. 1990. Efficacy of six fungicides against brown rot gummosis of
calamansi (Citrus madurensis). USM CA Res. Journal 1:120-124
Manalo JO & Tangonan NG. 1992. Fungicides for the control of stem canker of cocoa caused by
Phytophthora palmivora Butler. Plant Protection Paper No. 112 IN Cocoa Pests and Diseases
Management in Southeast Asia and Australia, FAO Via delle Terme di Caracalla, Rome, Italy
(Book Chapter), pp 153-155
Marcelino JP & Tangonan NG. 2008. Diseases of oil palm (Elaeis guineensis) in six municipalities
of Sultan Kudarat Province, Philippines. J Nature Studies 7 (2):49-56
Mondero NA, Evangelista RB, Tangonan NG, & Baltazar RB. 1991. Identification of castor bean
(Ricinus communis) diseases. USM CA Res. Journal 2:61-64
Nitafan JH, Tandigan IC, & Tangonan NG. 1991. Some variations in three isolates of
Phytophthora palmivora Butler causing black pod rot in cacao. USM CA Res. Journal 2:74-88
Noble IC Jr, Silvestre JC, & Tangonan NG. 1990. Incidence and chemical control of pink disease
of citrus caused by Corticium salmonicolor B. & Br. USM CA Res. Journal 1:174-181
Pedrajas AE & Tangonan NG. 1989. Incidence and infectivity of Physoderma brown spot of
corn at USMARC-USM, Kabacan, Cotabato. Philipp. J. Crop Sci. 14:89, Abstr
Ramos MA & Naomi G Tangonan. 2009. Identification of diseases of passion fruit (Passiflora
edulis F. flavicarpa Deg.) in selected municipalities of North and South Cotabato, Philippines.
USM R & D Journal 17(1):127-133
47
Sollorin LB & Tangonan NG. 1990. Trichoderma sp as biological control against Sclerotium
rolfsii causing damping-off in cotton (Gossypium hirsutum L.) seedlings. USM CA Res. Journal
1:181-185
Tangonan NG. 2007. Diseases of rubber in the Philippines In Rubber Manual for Smallholders
in the Philippines by EA Alcala 1st Edition, USM-Philippine Rubber Board, Inc. (PRBI), Book S.
No.1, pp 39-42
Tangonan NG. 2006. Diseases of Rubber (Hevea brasiliensis) in the Philippines: control and
screening for resistance, International Rubber Research Development Board (IRRDB) and
Rubber Research Institute of Vietnam (RRIV), Proceedings of the International Natural Rubber
Conference (INRC), The Legend Hotel, Ho Chi Minh City, Vietnam, November 13-17, 2006
Tangonan NG. 2006. Incidence, host range, and control of white root rot disease of rubber in the
Philippines, Proceedings of the International Workshop on White Root Rot Disease of Hevea
Rubber (Country Report), November 28-29, 2006, Salatiga, Indonesia, Indonesian Rubber
Research Institute and the International Rubber Research and Development Board, pp 42-56,
ISBN 978-979-25-3284-5
Tangonan NG. 2005. Some updates on diseases of rubber in the Philippines and their control,
Proceedings of the 1st International Rubber Conference and Centennial Celebration, November
22-24, 2005, Waterfront Hotel, Davao City
Tangonan NG & Alojado AB. 2006. Bio-efficacy evaluation of Organica on the incidence of
major pests and diseases of tissue-cultured cooking Cardava banana, http://organica.walkertaiwan.com/banana_ph2006
Tangonan NG & Butardo EGG. 2005. Control of Phytophthora black stripe disease of rubber in
Matalam, Cotabato. Journal of Tropical Plant Pathology 41:70-76
Tangonan NG, Pecho JA, & Butardo EGG. 2007. Disease Profile of Crops in USM, Kabacan,
Cotabato, USM, Kabacan, Cotabato ISBN 971-8676-18-X, 31 pp Brochure
Tangonan NG, Pecho JA, & Butardo EGG. 2008. Technoguide on Diseases of Rubber and their
Control, DA-BAR-funded, USM, Kabacan, Cotabato ISBN 971-8676-17-1,53 pp Brochure
Tangonan NG, Evangelista CC, & Ruano CP. 2005. Development of integrated pest and
disease management for citrus. USM R & D Journal 13(2):219-248
Tangonan NG & Solilap VE. 2003. Sclerotium rolfsii causing fruit rot of jackfruit (Artocarpus
heterophyllus L.). Journal of Tropical Plant Pathology 39:70-72
Tangonan NG. 2003. Cacao diseases and their management, Description and Management in
Cacao Production Technology Manual, SUCCESS-Alliance Philippines Project, ACDI-VOCA,
Cocoa Foundation of the Philippines-USAID-NAFC-DA, pp 53-68
48
Tangonan NG & Escopalao VM. 2002. Rhizoctonia disease of salago (Wikstroemia lanceolata
L.) in the Philippines and its control. Journal of Tropical Plant Pathology 38:9-15
Tangonan NG. 2002. Common fungal diseases of rubber (Hevea brasiliensis Muell. Arg.) in the
Philippines I. Incidence and symptomatology. USM R & D Journal 10(2):11-20
Tangonan NG. 2002. New records of fungal plant diseases in Cotabato, Mindanao, Philippines
USM R & D Journal 10(2):194-197
Tangonan NG. 2000. Host index of plant diseases in the Philippines: current status. Review
Article. Annual Report of the Research Center for Pathogenic Fungi and Microbial Toxicoses,
Division of Ultrastructure and Function, Department of Molecular Function), Chiba University,
Chiba 260-8673, Japan, pp 71-74
Tangonan NG. 1999. Host Index of Plant Diseases in the Philippines 3rd Edition, 408 pp, ISBN
971-9081-04-X, DA-PhilRice-USM, Maligaya, Muñoz, Nueva Ecija & USM, Kabacan, Cotabato
Tangonan NG & Escopalao VM. 1999. Leaf blight disease of coffee caused by Rhizoctonia
solani Kuhn. Philipp. J. Crop Sci. 24(1): 28, Abstr
Tangonan NG & Cuambot FD. 1998. Rhizoctonia solani causing leaf blight of durian. Philippine
Phytophathology 33(2): 130-133
Tangonan NG & Cuambot FD. 1998. Leaf blight of lanzones: 1st report. USM R & D Journal
6(1 & 2): 121-123
Tangonan NG. 1997. Anthracnose leafspot of alugbati (Basella rubra L.) caused by
Colletottrichum gloeosporioides Penz. USM CA Res Journal 8(2):196-197
Tangonan NG, Sebastian FA, & Cuambot FD. 1996. Phytopathological note: etiology of white
root rot of rubber. USM R & D Journal 4(1): 9-12
Tangonan NG & Natoc EH. 1994. Studies on biological control of plant diseases in the University
of Southern Mindanao, Kabacan, Cotabato, Philippines: 1978-1994. USM R & D Journal 2(1):
189-200
Tangonan NG. 1994. New foliar disease on peanut at USMARC noted. USM CA Res. Journal
4(2):214
Tangonan NG, Miral PR, Evangelista RB, & Garcia AV. 1993. Phytopathological note: incidence
of knob gall disease in immature rubber. USM CA Res Journal 4(1): 135-138
Tangonan NG. 1992. A review of the University of Southern Mindanao’s primary scientific
publications: 1968-1991. USM CA Res. Journal 3: 88-104
49
Tangonan NG & Dalmacio SC. 1992. Diseases of sorghum in the Philippines. In Sorghum and
Millets Diseases: A Second World Review, ICRISAT pp. 35-40, India.
Tangonan NG, Rondon RB, Punzalan F, Atienzar AL, Miral PR, & Arguelles JA. 1991. Effect of
paclobutrazol (Cultar 25 SC) on disease and yield of calamansi (Citrus madurensis). USM CA
Res. Journal 2:48-58
Tangonan NG, Torreon FA, & Silvestre JC. 1990. Citrus dieback disease at USM, Kabacan,
Cotabato: incidence and identification of its causal pathogens. Philipp. J. Crop Sci. 15:823,
Abstr
Tangonan NG & Sanico PG. 1988. Disease incidence in jute accessions at SMARC-USM,
Kabacan, Cotabato. Philippine Phytopathology 24:17, Abstr
Tangonan NG & Quimio TH. 1986. Etiology of sorghum stalk rot complex in Mindanao. Philippine
Phytopathology 21: 20-27
Tuyan JM and Tangonan NG. 2005. Agronomic and disease profile of industrial crops at PICRIUSM, Lumayong, Kabacan, Cotabato. USM CA Res Journal 16(1&2):117-123
Valencia DE, Jover EM, & Tangonan NG. 1992. Efficacy of Isoprothiolane for the control of
rubber stem bleeding. Proc. 1st. PPS-SMD Conv. Nov. 11-12, 1991, Villa Victoria, Davao City,
pp. 29-34
50
About the authors
NGT currently the Vice President for Research and
Extension, is University Professor of USM and Scientist 1
(of the Scientific Career System, Department of Science and
Technology) who has been working closely with JAP and
EGGB (Research Assistants in the Plant Pathology Research
Lab, USMARC) for some years now. They work as a team
in crop protection and plant disease R & D, trainings and
seminar-workshops among farmers, technicians, students,
and have presented their outputs in local, national, and
international scientific conferences. Their team-up has
brought them to different places in the country and along the
way have been blessed with new friendships and clientele not
to mention some local and regional awards (e.g., Best Paper
and Best Poster).
They hope this brochure may spark a new or continuing
interest in the field of plant pathology and pave the way to
a broader and more comprehensive publication on plant
diseases in the future; more importantly, that this guide will
help the beginner learn basic disease diagnosis, a key factor
crucial to devising effective control measures or management
interventions for better crop yields and higher profits.
The
UNIVERSITY OF SOUTHERN MINDANAO
The University of Southern Mindanao (USM) is a state university
created by virtue of Presidential Decree No. 1312 dated March 13, 1978
which effected its conversion from the former
Mindanao Institute of Technology (MIT),
then a state college established by virtue of
Republic Act No. 763 on June 20, 1952.
As a state university, its highes6 governing and policy making body
is the Board of Regents with the Commissioner of Commission on
Higher Education Department (CHED) as Chairman.
The University President administers the Institution.
Campus Site
The University main campus lies on a 1,024-hectare land grant situated in the
Municipality of Kabacan, Cotabato (Region XII), Philippines. It is 0.6 kilometer
north of the national highway connecting the cities of Cotabato and Davao,
about 10 kilometers from the junction of the Makilala-TacurongGeneral Santos Road and about 3 kilometers from the junction of the
Cotabato-Davao Sayre Highway.
Vision
Quality and relevant education for its clientele to be globally competitive,
culture sensitive and morally responsive human resources for development.
Mission
To accelerate the socio-economic development, promote harmony among the
diverse cultures in Southern Philippines, and improve the quality of life
through instruction, research, extension and production.
Core Values
Goodness
Responsiveness
Excellence
Assertion of Right and
Truth