This document provides information on guava wilt and cotton wilt diseases. It discusses the pathogens that cause each disease, including Fusarium oxysporum f. sp. psidii for guava wilt and Fusarium oxysporum f.sp. Vasinfectum for cotton wilt. It outlines the symptoms, disease cycles, favorable conditions, management strategies, and importance of each disease. Guava wilt reduces yields by 80% in affected orchards and has caused the uprooting of hundreds of acres of guava in some states. Cotton wilt is found in all cotton growing areas and is more prevalent in black cotton soils.

1. WELCoME
Presentation on
Guava Wilt and Cotton Wilt

3.  Wilt is a pernicious disease of guava in India.
In India the disease was first recorded near
Allahabad in 1935 . The infection was reported 15 -
30 %.
The disease is a serious threat to guava cultivation
in U.P. In West Bengal it reduces the yield in
affected orchard by 80% .
The disease is also prevalent in Haryana Rajasthan
, A.P , Punjab and M.P.
It has forced uprooting of about 150 acre of guava
orchard in Panjab and 300 acres in Haryana during
1971-81.
OCCURENCE AND IMPORTANCE

4. The exact cause of the disease is still not fully
understood but the pathogens viz. Fusarium
oxysporum f. sp. psidii (Prasad, Mehta & Lal),
Rhizoctonia bataticola Marcrophomina phaseoli
and various pathogens are reported by different
workers may be the incitant of the disease.
Survival and spread:
Through movement of plants containing sick soil
in virgin areas.
 Short distance spread is by water.
Root injury predisposes wilt disease.
ETIOLOGY

5. Favourable conditions
 High rainfall during August/ September.
 Stagnation of water in guava field for long duration.
 Maximum and minimum temperature ranges 23-32 °C
with 76% RH are conducive.
Lack of timely application of suitable control measures.
There is severe incidence of wilt in alkaline soils at pH
ranging from 7.5 to 9.0 or in lateritic soils at pH 6.5 .
Guava seedlings are more susceptible to F. solani as well as
F. oxysporum f.sp. psidii than older plants of 3 years age.
On the other hand researchers reported that F. solani could
infect guava plants from 1-month-old to more than 4 years
old.

6. SYMPTOMS
The leaves shed of
premature , fruit size remain
smaller, bare twig fail to
develop new leaves and
flower dry up.
 Browning and wilting of
leaves from tip.
Discolouration of stem and
death of branches and then
the whole tree dry up.
 The inner part of stem and
root upto cambium and
vascular tissues show a
distinct discolouration.

7. DISEASE CYCLE

8.  Proper sanitation.
Soil solarization.
 Uprooted and burnt wilted plants.
 Severe pruning followed by a drench with .2 %
Benlate or Bavistine 4 times in a year.
 Injection guava plant with 0.1 % water soluble 8-
quinolinol sulphate may provide protection against
wilt for at least 1 year.
 Use of resistant and tolerant varieties like ,
Allahabad Safeda , Dholka , Sindh etc.
MANAGEMENT

9. Wilt of cotton(Fusarium wilt)
Importance and occurence
Found in all cotton growing areas.
Believed to be started from Mexico or
central America.
Disease more prevalent in black cotton
soil which are heavy clay with an alkaline
reaction.

10. ETIOLOGY AND SYMPTOMS
Fusarium oxysporum f.sp. Vasinfectum
 The earliest symptoms appear on the seedlings in
the cotyledons which turn yellow and then brown.
 The earliest symptoms appear on the seedlings in
the cotyledons which turn yellow and then brown.
 In young and grown up plants, the first symptom
is yellowing of edges of leaves and area around
the veins, i.e. Discolouration starts from the
margin and spreads towards the midrib.

11.  Owning or blackening of vascular tissues is
the other important symptom, black streaks
or stripes may be seen extending upwards to
the branches and downwards to lateral
roots.
 In severe cases, discolouration may extend
throughout the plant.
 In transverse section, discoloured ring is
seen in the woody tissues of stem.

12. Fig:- Marginal chlorosis
and necrosis
Fig:- Browning of vascular
bundles

13. DISEASE CYCLE
 The fungus can survive in soil as saprophyte
for many years and chlamydospores act as
resting spores.
 The pathogen is both externally and internally
seed-borne.
 The primary infection is mainly from dormant
hyphae and chlamydospores in the soil.
 The secondary spread is through conidia and
chlamydospores which are disseminated by
irrigation water.

14. EPIDEMIOLOGY
 Soil temperature of 20-30 0C, hot and dry
periods followed by rains.
 Heavy black soils with an alkaline reaction,
increased doses of nitrogen and phosphatic
fertilizers, soil amendment with manganese and
wounds caused by nematode (Meloidogyne
incognita) and grubs of Ashweevil
(Myllocerus pustulatus).

15. MANAGEMENT
 Treat the acid-delinted seeds with Carboxin or
Chlorothalonil at 4 g/kg or Carbendazim@2g/kg seed.
 Remove and burn the infected plant debris in the soil after
deep summer ploughing.
 Apply increased doses of potash with a balanced dose of
nitrogenous and phosphatic fertilizers.
 Apply heavy doses of farm yard manure or other organic
manures at 10 t/ha.
 Follow mixed cropping with non-host plants.
 Grow disease resistant varieties of G. hirsutum and G.
barbadense like Varalakshmi, Vijaya, Pratap,Jayadhar,
Jarila, Jyothi, G 22 and Verum, HD 324, HD 432.

16. Thank you