May 8, 2015

Pests and Disease Management in Avocado


Disease
Symptoms
Cause
Comments
Management
Anthracnose
(Glomerella Cingulata)
Dead leaf tip, defoliation, brown or purple lesions and necrotic spots
Fungus
Spread by rain, high moisture and warm temperatures encourage spread
Prune dead twigs and branches from tree before fungi produce spores, remove dead leaves
Scab
(Sphaceloma perseae)
Irregular brown or purple spots on fruit with rough texture
Fungus
High humidity encourages scab growth and spread
Spray copper containing fungicides
Stem-end rot
Shriveled tissue at stem end, black lesions at stem and eventually over entire fruit
Environmental conditions, spores can spread by wind or rain
Prune dead limbs and twigs, prune and harvest in dry conditions, apply thick layer of mulch
Phytophthora Root Rot
(Phytophthora cinnamom)
Black lesions on roots, black, brittle roots, small yellow leaves, decline in fruit yield
Oomycete
Wet soils encourage Phytopthora infection, plant in a well drainage soil
Prune out dead limbs and twigs, remove fruit from the ground, Minimize wet splash between trees
Bacterial soft rot
(Erwinia herbicola
Erwinia carotovora)
Gray to black, mushy, foul smelling rot on fruit
Bacteria may be present on leaves but do not cause damage unless plant is stressed or bacteria enter the plant through a wound
No treatment for disease, remove plant debris from soil, use certified seed
Sunblotchs
(Avocado sunblotch virodi – ASBV)
Red, yellow, pink or white streaks running the length of young stems
Viroid
Can be transmitted by grafting
Sanitize all pruning equipment with disinfectant
Western Avocado Leafroller ( Amorbia)
Defoliation of tree, scarred fruit, young larvae are yellow-green and mature to dark green and a short, dark horizontal line on the side of thorax
Insect
Female can lay between 150 to 200 eggs during her life time, insect generally undergoes 3 generations per year
Application of selective insecticide such as Bacillus thurengiensis help to conserve populations of natural enemies
Avocado thrips
(Scritothrips perseae)
Feeding scars on fruit,adult insect is orange-yellow in color with distinct brown bands
Insect
Insect thrives in cooler temperature, insect may undergo 6 or more generations per year
Organic mulch about  6 inches thick below trees may help to reduce survival of thrips pupating  in soil, insecticide recommended to reduce damage to populations of natural enemies
Algal leaf spot
(Cephaleuros virescens)
Orange red-spots on both upper and lower surfaces of leaves, spots may coalesce to form irregularly shaped patches
Alga
Disease affects many fruit trees in the tropics, infection is unsightly but often harmless
Ensure trees are properly pruned and fertilized to promote vigor, remove all weeds from around tree bases, badly infested trees can be treated with copper containing fungicides
Persea mites (Oligonychus perseae)
Defoliation, mites cause the development of circular chlorotic to brown spots on the undersides of the leaves and fruit surface
Arachnid
Persea mites are most damaging on Hass and Gwen varieties
Ensure the tree is adequately fertilized, pruned properly and irrigated to avoid unnecessary stress to the tree
See also :
Types of Animal Manures to Increase Organic Content
Pests and Disease Management in Banana
Pests and Disease Management in Lemon

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Pests and Disease Management in Avocado
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Oleh