1) Sunflower crops can be affected by over 30 diseases caused by fungi, bacteria, viruses, and nematodes. 2) The document identifies and provides details on many common sunflower diseases such as downy mildew, rust, septoria leaf spot, and nematodes. It describes symptoms, life cycles, and impact of these diseases. 3) Control of sunflower diseases requires understanding their identification, life cycles, and favorable conditions to prevent and manage yield losses.

2. Sunflower Crop Diseases
A Presentation To IPM Course/FFS
Participants
By
Mr. Allah Dad Khan
Provincial Coordinator IPM KPK For
MINFAL Pakistan

7. Diseases
Sclerotinia head rot damaged fieldAt least 30
diseases, caused by various fungi, bacteria and
viruses, have been identified on wild or
cultivated sunflower, but only a few are of
economic significance as far as causing yield
losses. This section identifies many of the
diseases affecting sunflower crops and
provides information about the disease, its
impact, and control measures.

9. Apical Chlorosis
Identification and Life Cycle
• Apical chlorosis is caused by the
bacterium Pseudomonas syringae pv.
tagetis. Although infected plants are
conspicuous in the field, the disease is
of little economic importance. The
disease is most severe on seedlings
during cold, wet weather. The pathogen
can be disseminated among plants by
splashing rain and irrigation water, by
wind as aerosols, and by the movement
of contaminated soil. The apical
chlorosis pathogen is a very common
resident on the leaves of many weeds
and other crop plants, but also survives
in the soi
Cultures of Pseudomonas
syringae

10. Bacterial Leaf Spot
• Disease by P. syringae tends to be favoured by
wet, cool conditions—optimum temperatures
for disease tend to be around 12–25 °C,
although this can vary according to the
pathovar involved. The bacteria tend to be
seed-borne, and are dispersed between plants
by rain splash
• Symptoms

11. Bacterial Wilt
Symptoms
• Septoria blight causes numerous
small ( about 1/8" to 1/4" in
diameter) brown spots that
develop light tan to white center
as they age. The overall effect of
both blights is similar. Leaves turn
yellow, brown, then wither and
die. Septoria blight and early
blight both overwinter on
infected debris from previous
years. If there are only a few
plants in a garden, the progress of
the blights may be slowed
somewhat by removing infected
leaves as they appear.

12. Crown Gall
Symptoms
• Crown gall is caused
by Agrobacterium tumefaciens, a
Gram-negative, bacilliform
bacterium that is normally
associated with the roots of many
different plants in the field. This
bacterium can survive in the free-
living state in many soils with
good aeration such as sandy
loams where crown gall diseased
plants have grown. The bacterium
can also survive on the surface of
roots (rhizoplane) of many
orchard weeds.

14. Alternaria Leaf Blight

16. Downy Mildew
Damage:
• Seedling infection seldom
exceeds 25 percent of the field,
although there have been
exceptions. The infected plants
die off very early and do not
compete for nutrients with
neighboring plants. If the
infection is sporadic throughout
the field, the compensating
ability of sunflower will
compensate and the yield impact
will be minimal. However, if all or
a majority of the plants in a part
of the field are infected then the
damage will be significant.

17. Powdery Midew

19. Rust

21. Septoria Leaf Spot
Identification and Life Cycle
• Septoria leaf spot is caused by the
fungus Septoria helianthi. Little is
known about the survival and
dissemination, but the disease cycle is
thought to begin when spores (conidia)
are deposited onto leaves by wind
and/or splashing water. The fungus
directly penetrates host tissues, and
develops fruiting structures (pycnidia)
that produce more conidia. The disease
develops most rapidly during moderate
to warm weather with abundant
rainfall, especially after flowering. The
fungus can be seedborne, and is
thought to survive between sunflower
crops in and on infected crop debris.

23. Pin Nematodes
Symptoms
• Pin nematodes rarely cause damage to
plants unless present in very high numbers.
However, mint is one of the best hosts for
pin nematodes, and populations frequently
exceed 100,000/quart soil. Effects of feeding
by pin nematodes on the appearance,
structure or function of mint roots has not
been studied. In other crop plants,
symptoms range from no noticeable
pathology at the feeding sites to shallow
localized lesions. Rate of root growth and
lateral root development may be reduced or
terminated by the prolonged feeding of
many individuals on the same root. This
may reduce the nutrients, and thus energy,
which can be stored into the rhizome,
potentially reducing the health and vigor of
the plants.

24. Lesion Nematodes
Symptoms
• Symptoms of lesion nematode
disease (as with most nematode-
induced diseases) often go
unrecognized initially because the
nematodes (Figure 1) are
microscopic pathogens of
belowground plant parts (mainly
roots), and the aboveground
symptoms are often general
symptoms of plant root stress.
Low to moderate populations of
lesion nematodes may cause no
visible aboveground symptom
Lesion nematode inside root

25. Root Knot Nematodes
Symptoms
• Root-knot nematode symptoms on
plant roots are dramatic. As a result of
nematode feeding, large galls or
"knots" can form throughout the root
system of infected plants. Severe
infections result in reduced yields on
numerous crops and can also affect
consumer acceptance of many plants,
including vegetables (Figures 1, 2). The
degree of root galling generally
depends on three factors: nematode
population
density, Meloidogyne species and
"race," and host plant species and even
cultivar. As the density of nematodes
increases in a particular field, the
number of galls per plant also will
increase
On carrot

26. Spiral Nematodes
Symptoms
• The symptoms of Helicotylenchus
pseudorobustus are more subtle
than those of certain other
nematodes such as root-knot or
sting nematodes. Heavy infection
byHelicotylenchus
pseudorobustus causes a
reduction in the root system,
leading to unthrifty plants. On
turfgrasses, Helicotylenchus
pseudorobustus has been shown
to reduce root length and cause
thinning of turf. Generally the turf
decline will occur in patches

27. Stunt Nematodes
• Stunt nematodes damage the roots of field
and vegetable crops. Once damaged, plants
become exposed to many destructive
soilborne microorganisms and pathogens. A
major problem with determining the damage
these nematodes cause is inadequate
knowledge of their distinguishing
characteristics, numbers, relationships and
geographic distribution.
• Symptoms

29. Aster Yellow
• Aster yellows is a virus-like disease caused by a
phytoplasma, an organism similar to a bacterium. The
aster yellows phytoplasma is vectored by the aster
leafhopper, an olivegreen or straw-colored leafhopper
with six dark spots on its forehead. Aster leafhopppers
migrate from the south, usually arriving in early to mid
June. Serious outbreaks of aster yellows can be caused
by large numbers of migrant leafhoppers in the spring,
warm weather in May and June, and adequate
precipitation and soil moisture. The aster leafhopper
will not fly at temperatures below 60°F
• Symptoms

30. Sunflower Mosaic
Identification and Life Cycle
• Sunflower mosaic can be caused
by three different viruses, namely
Cucumber mosaic virus,
Sunflower virus, and Tobacco
mosaic virus. The most common
virus causing sunflower mosaic is
Cucumber mosaic virus. This virus
can be mechanically- and
aphidtransmitted and has a broad
host range. Aphids can acquire
and transmit Cucumber mosaic
virus within 5 to 10 seconds of
feeding. The virus can overwinter
in many ornamental plants and
weeds.

31. Chlorotic mottle
• Symptom development in a susceptible
sunflower line inoculated with Sunflower
chlorotic mottle virus (SuCMoV) was followed in
the second pair of leaves at different post-
inoculation times: before symptom expression
(BS), at early (ES) and late (LS) symptom
expression. Sugar and starch increases and
photoinhibition were observed as early effects
BS, and were maintained or enhanced later on,
however, chlorophyll loss was detected only at LS.
Photoinhibition correlated with a drastic decrease
in D1 protein level

32. Other Diseases