PATH 372 Diseases of Horticultural Crops

Mode of spread: Diseased leaves serve as primary inoculum. Scale insects and aphids,
Lecanium hemisphaericum, L. viride, L. nigrum, Hemilecanium imbricans and Pulvinaria
Psidii.
Management:
Controlling of plant hoppers by spraying Carbaryl (2g/lt) or Phosphomidon 0.03%
Spray dilute solution of starch or maida 5% (Boil 1 kg of maida or starch in 5 litres of
water, cool and dilute to 20 litres), which dries up and comes off in flakes, removing
along with it the sooty mold growth.
6) Red rust: Cephaleuros virescens (algae)
Economic importance: In India it has been observed in Bihar, Karnataka and U.P. The
disease appeared in an epidemic form in orchards of Tarai in 1956. Reduction in
photosynthetic activity and defoliation as a result of algal attack lower vitality of the host
plant.
Symptoms:
The disease is characterized by red rusty spots on the leaves and young twigs
The spots are initially circular, slightly elevated and later coalesce to form irregular
spots.
The upper surface of the spot consists of numerous unbranched filaments of the
pathogen which project through the cuticle. Some of the filaments represent the sterile
hairs while others the fertile ones
Initially the spots are greenish-grey in colour and variety in texture, but later on the
surface bears reddish-brown appearance.
Disease cycle: Common in close plantations. High moist conditions favour the
development of fruiting bodies.
P.I.- Zoospores.
Management:
Avoid close plantations
Spray Bordeaux mixture 1-2% or Fytolan / Blitox 0.5% or lime sulphur 0.1%
7) Loranthus
Symptoms:
Loranthus is a partial stem parasite. Loranthus seeds are disseminated by birds on to
the stems of the host.
Loranthus seeds do not require a host germination stimulus and will germinate
spontaneously.
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