Nectarine Diseases A

Lecture To ToT trainees ( FFS)

By Mr. Allah Dad Khan

Provincial Coordinator IPM KPK

MINFAL Pakistan

Peach Brown Rot

Symptoms Brown rot on fruit Brown rot, caused by the

fungus Monilinia fructicola, causes the fruit to rot away while still on the tree. In its last stages the fruit is entirely brown and looks whithered and dried out. The fungus can live in many temperatures and climates, but it particularly loves moist climates. The rot can also turn flowers brown and cause new twigs to die off.

To prevent the spread, make sure to clear away affected fruit, twigs or flowers. Do not compost the remains, as the fungus spores can live in compost and spread to the rest of your garden. A fungicide can also stop the spread of the fungus. Good air circulation and a drier enviornment also helps prevent rot.

Peach Brown Rot Symptoms of brown rot on peach blossom

Symptoms of brown rot on peach twigs and blossoms

Peach Brown RotSymptoms of brown rot on fruits Brown rot on fruit

Peach ScabCladosporium carpophilum

Symptoms Scab on peach fruit Peach scab is caused by a fungus

called Cladosporium carpophilu. It is most often found in warm, moist and humid areas, such as in the South. However, it can affect peach trees worldwide. The fruit will often crack and rot within those cracks, without much affect to the taste of the fruit. However, scab makes it harder for the peach skins to slip off during the canning process.

To prevent scab, use a chemical or organic fungicide just as the blossoms fall of the trees and for the ensuing month. Pruning and cleaning up fallen fruit and leaves will also prevent the continued spread.

Peach Scab Scab symptoms on peach twigs

Scab symptoms on peach fruit

Peach Scab Scab symptoms on peach fruit

Scab symptoms on peach fruit

Peach Powdery Mildew

Symptoms Powdery Mildew is caused by

the fungus called Sphaerotheca pannosa and affects both garden plants and fruit trees. Leaves often fall off or develop abnormally, eventually growing a white fuzz. An entire harvest can be ruined by mildew if left unattended. Consider purchasing tree varieties that aren't susceptible to the disease. Fungicide and proper area maintenance are also good preventative practices.

Peach Leaf Curl

Symptoms Leaf curl on peach Leaf curl is a fungal

disease caused by Traphrina deofrmans. It causes defoliation and crop loss in practically every variety of peach tree. Fungicide application during the fall after most of the leaves have fallen or before budding in spring can stop the fungus.

Leaf curlPeach leaf infected with leaf curl

Peach leaf curl symptoms

Peach Leaf Curl Peach leaf curl symptoms on young peach tree

Peach leaf curl symptoms on foliage

Peach Leaf curl Peach leaf curl symptoms

Peach leaf curl symptoms

Peach Bacterial cankerPseudomonas syringae

Symptoms Canker on peach trunk Cankers on twigs at bases of flower and leaf buds,

in pruning wounds or at the base of spurs which exude amber colored gum; cankers spread upwards and form sunken areas in winter; if pathogen enters dormant buds they may be killed or open normally in Spring before collapsing in early Summer; infected buds may be symptomless

Cause Bacterium Comments Disease emergence favors high moisture and low

temperatures in the spring; young trees particularly susceptible; trees grown in sandy soils that drain poorly are also susceptible

Management Ensure that a suitable peach variety and rootstock

is chosen based on geographic location and environmental conditions to prevent stress to tree which predisposes tree to canker disease; apply protective copper spray to trees before flowering; prune trees in early summer to decrease likelihood of infection

Peach canker Canker exuding gum on infected peach tree

Peach tree with dark cankers on bark

Canker on peach trunk

Canker on peach trunk Canker on peach trunk (bark peeled to show discoloration to tissue underneath)

Bacterial spot Xanthomonas campestrisSymptoms Peach tree infected with

bacterial spot Water soaked, angular gray lesions on the underside of the

leaves which turn purple and necrotic in the center and cause a shot hole appearance if lesion center drops out; if lesions are present in high numbers on leaves they may become chlorotic and drop from tree; cankers develop on twigs either as raised blisters or as a dark area surrounding a bud that fails to open; in years of severe infection the entire fruit crop may be lost; lesions on fruit begin as small brown, water-soaked lesions which may exude gum

Cause Bacterium

Comments Periods of frequent rainfall during late bloom and early

petal drop increase likelihood of fruit and leaf infection; infection is rare during hot, dry weather

Management Avoid planting susceptible peach varieties in areas where

disease is known; once disease is visible it can be difficult to control, protective copper applications in the Fall prior to leaf drop and/or application in early growing season may help prevent the disease; care should be taken as peach trees are very sensitive to copper

Peach Bacterial Spot Symptoms of bacterial spot on peach leaves

Symptoms of bacterial spot on peach leaves

Peach Bacterial Spot Symptoms of bacterial spot on peach leaf

Symptoms of bacterial spot on peach fruit

Peach Crown gallAgrobacterium sppSymptoms Large gall on trunk of peach

tree Galls on roots and/or crown of tree which can range

in size from so small they are not visible to the naked eye up to 10 cm (4 in) in diameter; galls first become visible as white, fleshy swellings that grow rapidly and become tan to brown in color; galls typically develop at the site of a wound and new galls form adjacent to old ones the next year

Cause Bacterium Comments Infection with crown gall begins at the site of plant

wounds; disease emergence is favored by poorly-drained, alkaline soils and previous feeding damage by nematodes

Management Chemical control of the disease is generally

ineffective; an effective bacterial biological control is available for commercial production; cultural control methods include: planting only certified, disease-free material, planting peach in well-draining soil, rotating infected fields with a non-host before peach is planted and also using good sanitation practices

Crown GallSymptoms of crown gall on trunk of peach tree

Galls on roots of peach tree

Crown Gall

Crowm gall symptomsSymptoms of crown gall on trunk of peach tree

Crown Gall

Gall on peach tree Galls on peach roots

Peach Shot hole diseaseWilsonomyces carpophilus

Symptoms Shot hole lesions on peach fruit

Brown lesions with purple edge on fruit, twigs and buds; holes in leaves due to lesions which have dried and dropped out; brown lumps developing in the center of lesion (visible with hand lens); buds turning brown or black and exuding sap; tan lesions with brown margins which exude sap on twigs

Cause Fungus Comments Disease emergence favors wet, windy

conditions Management Application of Bordeaux mixture before

rains in Fall are sufficient to protect dormant buds and twigs over winter

Shot Hole Shot hiole symptoms on peach fruit

Shot hole lesions on peach fruit

Peach Silver leaf diseaseChondrosterum pupureum

Symptoms

Leaves have a silvery appearance; if infection is severe the leaves may curl upwards and become necrotic; death of individual limbs or entire tree may occur; fungal fruiting bodies appear on the surface of the dead bark

Cause Fungus Comments Pathogen is spread via spores released after rainfall

during periods of high humidity and can enter trees through pruning wounds; risk of infection is increased if tree is pruned during late winter or early spring; trees also susceptible when they are heavily pruned

Management Control of silver leaf disease is difficult and infection

can be widespread after rainfall in areas where the disease is present; strategies to reduce the incidence of the disease include: removing all plant debris e.g. pruning waste, stumps, and logs; pruning tree during dry periods and treating large pruning wounds with fungicidal dressing

Phytophthora root and crown rotPhytophthora spp.

Peach tree showing symptoms of Phytophthora infection

Peach RustTranzschelia discolor

Symptoms Rust spots on peach leaves

Pale yellow-green spots on both upper and lower leaf surfaces which are angular in shape and turn bright yellow in color; spots on lower leaf surface develop orange-red spores

Cause Fungus Comments Fungus overwinters in twigs or in leaves

which remain attached to the tree Management Rust can be prevented by spraying trees

with protective fungicides; application is usually carried out one, two and three months before harvest in areas prone to early season outbreaks of the disease and after harvest in areas where disease is less problematic or emerges later in the season

Peach Rust Rust symptoms on peach leaves

Rust symptoms on peach leaves

Plum pox virusPlum pox virus (PPV)

SymptomsSymptoms of plum pox on peach fruit

First expanding leaves exhibit chlorotic veinclearing and veinbanding; lamina twisted and distorted; fruit show dark rings, lines and spots; symptoms on fruti may disappear on ripening; fruit may be deformed

Cause Virus Comments Virus is transmitted by aphids but most

common method of spread is diseased plant material

Management Plant certified healthy material; remove

infected trees from orchard; chemical sprays to control aphids may prolong spread of virus

Peach Fruittree leafrollerArchips argyrospilaSymptoms

Fruittree leafroller Leaves of plant rolled and tied together with silk

webbing; feeding damage to rolled leaves; defoliation of plant; silk webbing may also be present on fruits and fruits may have substantial scarring from feeding damage; larvae wriggle vigorously when disturbed and may drop from plant on a silken thread

Cause Insect Comments Only one generation of insect per year Management Monitor plants regularly for signs of infestation;

remove weeds from plant bases as they can act as hosts for leafrollers; avoid planting pepper in areas where sugarbeet or alfalfa are grown nearby; Bacillus thuringiensis or Entrust SC may be applied to control insects on organically grown plants; apply sprays carefully to ensure that treatment reaches inside rolled leaves