PATH 372 Diseases of Horticultural Crops

LECTURE 3
DISEASES OF BER
1. Powdery mildew – Oidium erysiphoides f.sp. zizyphi
The disease is noticed generally at the end of October and prevails from
November to April
Symptoms
Powdery mass appears on young leaves and fruits
Severely affected leaves shrink and defoliate
Small white pwdery growth appear on young fruits which later enlarge and
coalesce and finally turn brown to dark brown in colour
Infected fruits become corky, crack, misshapen, underdeveloped and finally drop
prematurely
Survival and spread
P.I: Budwood of host plant
S.I: Air-borne conidia
Favourable conditions
Warm humid conditions with R.H more than 90%
Management
Spray Dinocap@0.1% or Wettable S@0.2% during first and third weeks of Nov
Two sprays of carbendazim@0.2% at 15 days interval, starting from the time when
the fruits are of pea size followed by Dinocap@0.1% spray at 10-15 days interval
Add Teepol or Sandovit to the fungicide solution
DISEASES OF GUAVA
1. Wilt – Fusaium oxysporum f.sp. psidii, F. solani, Macrophomina phaseolina,
Cephalosporium sp., Gliocladium roseum and Verticillium alboarum.
Economic importance: It was first reorted in 1935 from Allahabad. Jhoty et al., in
1984 reported that seven thousand acres of land in A.P under guava cultivation was
reduced to half the land value by the presence of the disease.
Symptoms
The affected plants show yellow colouration with slight leaf curling at the terminal
branches, becoming reddish at the later stage and subsequently premature shedding
of leaves takes place.
Twigs become bare and fail to bring forth new leaves or flowers and eventually dry
up. Fruits of all the affected branches remain underdeveloped, become hard, black
and stony.
The entire plantr becomes defoliated and dies. A few plants also show partial
wlting, which is very common symptom of wilt in guava.
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