This document discusses several diseases that affect cucurbit crops including anthracnose, fruit rots caused by fungi, leaf spots, fusarium wilt, downy mildew, powdery mildew, alternaria blight, rhizoctonia root rot, mosaic diseases, seed rot and damping off, bacterial leaf spot, scab, cucumber mosaic virus, gummy stem blight, watermelon mosaic virus, and cucumber green mottle mosaic virus. It provides details on symptoms for each disease and recommends control measures such as using disease-free seed and crop rotation, applying fungicides and insecticides, and removing infected plant debris.

1. Diseases of Cucurbits

2. Anthracnose
(Colletotrichum lagenarium)
 Disease sumptoms are
found on all plants parts
above ground started from
cotylodonary leaf to true
leaves, stem, fruits and
tendril in ash gourd
(Prakash et al., 1974).
 Light brown circular spots,
which later deep to turn
brown, appear on the
leaves.
 Later on infected fruit rot
and all the seed, which is
source of further primary
infection.
 It is seed borne disease
(Sohi and Maholy, 1974).

3. Control measure
 Collect the seed only
from disease-free plants.
 Avoid growing ash gourd
in field repeatedly used
for the cultivation of
cucurbits.
 Treat the seed with
Capton or Thiram @ 2.5
g/kg of seed before
sowing.
 Spray the systemic
fungicide such as 0.1%
carbendazim (Prakash et
al., 1974).
 Spray the hexaconazole
@ 0.025-0.05% also give
good result.

4. Fruit rots
fusarium solani, F. monoliformi, Verticillium dahliae
 Decaying of fruits is a major
problem during storage.
 Some time rotting start from
the lower fruit portion that had
been contact from the soil.
 White fungal growth, which
later on turn into brown
circular scelerotia, is observed
on fruit surface.
 The infected fruits contain
completely rotten seed, which
turn white, become hollow,
and fail to germinate (Pandey
et al., 2003).
 Brown dull spots, which lead
to softening, and rotting, are
developed on fruits
(Upadhayay and Roy, 1987).

5. Control measure
 Expose the soil following
repeated deep summer
ploughing.
 Adopt long crop rotation
with cearals and clean
cultivation.
 Use only healthy seed.
 Train the crop on bower
system to minimize the
infection.
 Treat the seed with
Trichoderma viridae
along with neem cake
application.
 Collect the infected fruit
and brunt.

6. Leaf spot
(Phoma cucurbitacearum)
 Black small dot like
structures are developed
on older leaves.
 White fungal growth is
clearly visible on outer
margins of the spots in
morning on under side of
leaves.
 Severely infected leaves
give burning appearance.
 The disease is more
common during winter
season.

7. Control measure
 Treat the seed
with
cardendazim @
0.25 % to
minimize the
infection in the
crop.
 Spray mancozeb
at 0.25% alterd
with one spray
of hexaconalzol
at 0.05%.

8. Fusarium wilt
(Fusarium oxysporum f. sp. benincasae)
 The disease more
common in sandy
soil.
 Yellowing of lower
leaves, which
gradually progress
on upper leaves.
 The plant soon after
infection starts
drooping followed
by wilting, later on,
wilting become
permanent.

9. Control measure
 Apply
Trichoderma @
5-8 kg/ha,
depending up
on the soil
structure, to
minimize
disease.
 Tret the seed
with
carbendazim @
2.5 g/kg of
seed.

10. Downy mildew
Pseudopernospora cubensis
 Generally, at initial stage,
small irregular yellowish
lesion appear on leaves.
 Old lesion become necrotic,
and they are clearly
demarcated with light
yellow areas.
 Downy mildew attacks
occasionally on ash gourd
(Uppal et al,. 1935).
 At Solan, downy mildew
was recorded on ash gourd
without oospores (Uppal et
al., 1935).

11. Control measure
 Grow the crop at wider spacing
on well-drained soils.
 Collect the seed from disease free
healthy fruits to avoid further
infection.
 Spray mancozeb @ 0.25% at
seven days interval.
 In severe conditions, follow one
spray of metalaxyl + mancozeb 2
0.2%.
 Spray copper oxychloride 0.2% at
10 days interval (Munshi and
Cohan, 1973).
 Field sanitation by burning crop
debris reduce the inoculums.

12. Powdery mildew
Erysiphe cicoracearum
 It is more severe under dry and
rain free weather conditions
although it is favored by hot and
humid weather, moderate
temperature and reduced light
intensity and succulent plant
growth (Khan et al., 1972).
 White long patches or powdery
coating appears first on the
under surface of the leaves,
which later spread to the upper
surface, stem, petiole and other
succulent plan parts.
 Severe infection cause stunted
growth and browning of leaves
followed by premature
defoliation.

13. Control measure
Collect and
burn all the
infected
leaves.
Carbendazi
m at 0.1% at
different
interval as
per need

14. Alternaria blight and
leaf spot
(Alternaria cucumeriana)
 Bitter gourd/Squash/Pumpkin/
Snake gourd
 The yield losses reported
are about 77% in bitter
gourd and 80% in
pumpkin.
 The initial infection is
noticed as small spots on
leaves, which rapidly
increase in number and
size.
 in advance-stages, the
burning effect and blight
symptoms are also seen.

15. Control measure
 Collecting and burning of
plant debris are effective
for reducing inoculums.
 Following crop rotation for
at least 3 year.
 Providing proper drainage
reduce the incidence of
this disease.
 Borax wash @ 2.5% at
45˚c for 30 second before
packaging of fruits reduces
incidence in storage.

16. Rhizoctonia root rot
Rhizoctonia solani
Mostly occur in
Bottle gourd.
The fungus cause
pre- and post
emergence mortality
of seedlings.
However, older
plants are less
susceptible to this
disease.

17. Control measure
 Follow long crop
rotation fo non
host crops.
 Treat the seed
with vitavex or
Brassicol 3-4
g/kg of seed.
 Drench the soil
with Brassicol @
0.2%.

18. Mosaic disease
 A large number of viruses
attack the bottle gourd crop
and cause serious damage.
 The leaves shows the
symptoms like, mosaic
mottling, crinkling, and
twisting.
 Internodes are shortened and
flowering is affected
adversely.
 In rainy season white fly
spread the virus rapidly.
 Infection during early stages
of growth (5-30 days) caused
up to 100% loss in yield
(Singh, 1989).

19. Control measure
Collect the seed
from virus fee
plants.
Spray the crop with
systemic
insecticides like,
Malathion @
0.05% at 5-7 days
interval to control
the virus vector.

20. Seed rot and damping off
(Pythium and Fusarium spp.)
 Mostly in cucumber.
 This pathogen frequently
causes seed rot, damping
off, seedling blight and
root rot in tropical and
subtropical zones.
 All pathogens are
affected by soil
temperature and
particular by moisture as
well as rainfall during
seedling stage (Goldberg
and Stanghellini, 1990).

21. Control measure
 Expose the soil to sun
by repeated vdeep
ploughing.
 Follow soil solarization
practice.
 Treat the seed with
Thiram or Captan @
2.0 g/kg of seed.
 Spray Mycostop
powder formulation
prepared from
Pseudomonas
fluorescence or
Streptomyces sp. Prior
and after planting.

22. Bacterial leaf spot
(Xanthomonas cucurbitae)
 Bacterial leaf spot is
quite common disease
of cucumber and
gherkin.
 The disease produced
symptoms as spots
(water soaked areas
enlarge and turn brown
with age surrunded by
a yellow halo) only on
leaf rarely on stems
and petioles.
 Optimum temperature
for pathogen survival is
around 25-30˚c

23. Control measure
 Soak seeds for 60
minutes in1: 20
dilution of commercial
HCL containing 1%
surfactant.
 Treat the seed with hot
water (54-56˚c) for 30
minutes or 1% sodium
hypochloride + 1%
surfactant for 40
minutes.
 Grow resistant cultivar
like, Japanease Long
Green.

24. Scab
(Cladosporium cucumerianum)
 The disease appears as
dark brown sunken
spots on stems and
fruits.
 In moist weather, these
spots are covered with
a greenish mould.
 Sometimes, a gum like
substances oozes from
the affected leaves and
fruits.

25. Control measure
 Adopt clean
cultivation and long
crop rotation.
 Spray Streptomycin at
400 ppm in standing
crop.

26. Cucumber mosaic/white
pickle mosaic
(CMV)
 It causes the 10-20% yield loss
in cucumber.
 This mosaic cucumo-virus
described as ‘’narrow leaf of
tomato in New Zealand’’,
cucumber green mottle mosaic
Tobamovirus (CGMMT) In
England and cucumber
necrosis, cucumber mosaic,
cucumber vein yellowing and
cucumber wild mosaic and
squirting cucumber mosaic in
other parts of the world.
 If the plants are infected with
CMV at cotyledonary stage, the
yield is reduced by 89 % in
summer and 96 % in rainy
season.

27.  It is characterized by
stunting of plants,
mottling, yellowing, and
wrinkling of leaves and
warting and mottling of
fruits.
 In cucumber, its
transmission through
seed was reported 37 % .
 The symptoms produced
by CMV are dry, brittle,
and necrotic lesions
along the leaf veins,
malformation and
internodes shortening,
vein clearing, wilting,
and drying, particularly
in cool weather.

28. Control measure
Use disease free
seed.
Collect and
destroy the
disease debris.
Eradicate the wild
host plants.
Spray Malathion
@ 2 ml/l of water
at 5-7 days
interval.

29. Gummy stem blight
(Didymella bryoniae)
 It is serious problem
in ivy gourd.
 Canker on stem,
petiole, and fruit stalk,
stem decay and wilt
are some common
symptoms appear
during infection.
 Watery scoop
exudates from the
nodal portion of the
stems, which turn
yellowish brown gum,
are other major
symptoms.

30. Control measure
Follow deep
ploughing during
summer.
Use disease free
healthy planting
material.
Collect and burn the
disease debris.
Harvest the fruit
carefully to avoid
injury.
Spray carbedazim
0.1% to reduce the
infection.

31. Watermelon
mosaic virus
(WMV)
 It is transfer through
sucking insect like,
Aphis gossypii,
(Pearson and
Liyanage, 1997).
 The symptoms appear
on leaves in the form
of curling mosaic or
mottling accompained
by green vein banding
and reduction in leaf
size.
 Sometimes, the
petiole and internodes
length also shortened.

32. Control measure
 Use disease free healthy
planting material.
 Follow wider spacing and
clean cultivation in well-
drained soil.
 Collect and destroy the
infected debris from the
field as soon as possible.
 Spray the crop with
Diamethoate @ 0.1% (I
ml/liter of water) to
reduce the population of
whitefly.
 Spray Emidacloprid @ 3
ml/liter of water at regular
interval to check the
vector.

33. Cucumber green mottle mosaic virus
CGMMV
 The major symptoms of
CGMMV are slight clearing of
veins and crumpling of the
younger leaves followed by a
light and dark green mottle to
gather with blistering and
distortion of leaves.
 The CGMMV was first time
reported from India in bottle
gourd (Capoor and Verma,
1948., Vasudeva et al., 1950).
 This virus is naturally infected
in musk melon (Sanker and
Nariani, 1974).
 The cucurbit beetle is able to
transmit the virus to extent 27
% (Rao and Verma, 1984).

34. Control measure
 Early sowing of crops
may reduce the
disease due to low
vector population.
 Avoid contamination
by worker and
implements.
 Spray Dimethoate or
metasystocs (1 ml/l) at
10 days interval to
manage the vector.

35. Angular leaf spot
Pseudomonas lachrymans
 The disease appear on leaves, stem
and fruits as small water soaked
spots.
 On leaves, they enlarge up to a
diameter of about 3 mm, becoming
tan on upper surface and gummy or
shiny on the lower surface.
 Lesion attain an angular shape as
they are delimited by veins.
 The necrotic centers of leaf spots
may drop out.
 On the stems, petioles and fruits the
water soaked spots are covered
with crusty bacterial exudates.

36. Control measure
 Follow field sanitation
and long crop rotation
as the preventative
measures to reduce
the inoculums.
 Destroy the disease
debris after harvesting
the crops.
 Treat the seed with
hot water at 54C for
30 minutes.
 Two sprays of
Streptomycin at 400
ppm or Bordeaux
mixture at 1%.

37. Water melon bud necrosis
WMBNV
The virus generally
transmitted by sap of
already infected plant
and thrips.
The first symptoms
appear on apical bud,
which turn brown to
black and die.
In certain cases,
broken or complete
concentric rings are
also developed on
fruit.

38. Control measure
 Use seed free from
virus disease.
 Spray systemic
insecticides
Dmethoate or
metasysytox @ 1
ml/liter periodically
up to flowering to
check the vector
activity.