AvacadoDiseases A

Lecture To ToT trainees ( FFS)

By Mr. Allah Dad Khan

Provincial Coordinator IPM KPK

MINFAL Pakistan

Anthracnose symptoms Anthracnose symptoms

AnthracnoseGlomerella cingulata

Anthracnose symptoms Anthracnose symptoms

Anthracnose

Anthracnose symptoms Anthracnose symptoms

Anthracnose

Symptoms

Chlorotic and necrotic spots; dead leaf tip; defoliation; brown or purple lesions on new shoots

Cause Fungus Comments Spores spread by rain splash; high

moisture and warm temperatures encourage spread

Management Prune dead twigs and branches from

tree before fungi produce spores; knock dead leaves out of canopy; keep harvested fruit dry and cool

Chloratic Disease

Avocado scab Scab symptoms

Scab Sphaceloma perseae

Symptoms

Oval or irregular brown or purple spots on fruit with rough texture

Cause Fungus Comments High humidity encourages scab

growth and spread Management Plant tolerant varieties; spray

with copper containing fungicides

Purple Spot

Symptoms

Elongated black streaks on bark; cankers parallel to growth of limbs; black blotches with distinct margins on green wood; cankers on bark cause cracks which ooze sap; removal of bark over cankers reveals dark discoloration underneath

Cause Unknown Comments Disease emergence favors adverse

growing conditions for avocado; more common in Guatemalan cultivars

Management Avoid stressing trees by following good

fertilization and irrigation practices

Black streak Avocado black streak

Symptoms

Black lesions on roots; black, brittle roots; small, yellow leaves; premature leaf drop; decline in fruit yield

Cause Oomycete Comments Wet soils encourage Phytophthora

infection; plant in a well draining soil.

Management Minimize water splash between trees

by not working in a wet orchard; prune out dead limbs and twigs; remove fruit from the ground; dispose of dead wood and fruit away from trees

Phytophthora root rot and crown rot Phytophthora cinnamomi

Fruit symptoms of P. citricola

Tree trunk with symptoms of Phytophthora citricola.

Phytophthora

Symptoms

Shrivelled tissue at stem end; dark brown or black lesions at stem end and eventually over entire fruit; fruit covered in mycelium

Cause Fungi Comments Environmental conditions may determine

which fungal species is most common; spores can spread by wind or rain.

Management Prune dead limbs and twigs; prune and

harvest in dry conditions; provide trees with sufficient irrigation; apply a thick layer of mulch

Stem-end rot

Symptoms

Symptoms Gray to black, mushy, foul smelling rot on

fruit; fruti has darkened metallic sheen

Cause Bacteria Comments Bacteria may be present on leaves but do not

cause damage unless plant is stressed or bacteria enter the plant through a wound

Management No treatment for disease; use certified seed;

disinfected tools and cuttings; employ crop rotation; remove plant debris from soil

Bacterial soft rot

Symptoms

Red, yellow, pink or white streaks running the length of young stems; white, yellow or red blotches on fruit

Cause Viroid Comments Can be transmitted by grafting Management Frequently sanitize all pruning

equipment with disinfectant; plant only certified nursery stock

SunblotchAvocado sunblotch viroid (ASBVd)

Algal leaf spot symptoms Algal leaf spot symptoms

Algal leaf spotCephaleuros virescens

Symptoms Algal leaf spot symptoms

Raised, orange-red spots on both upper and lower surfaces of leaves; spots may coalesce to form irregularly shaped patches; spots may also be present on twigs and branches; when the surface of the spot is scraped away, a gray to dark necrotic crust is visible

Algal Leaf Spot