Diseases and management of pear and corrective measure
- 1. PANDIT DEEN DAYAL UPADHAYAY COLLEGE OF HORTICULTURE AND FORESTRY ASSIGNMENT OF HPP-202 SUBMITTED BY NAME –ABHIJIT NAYAK Roll -1907101014 TOPIC- DISEASES OF PEAR SUBMITTED TO Respected Dr.Sangita Sahni ma’am Respected Dr. Phool Chand sir ASSIGNMENT OF HPP-202 SUBMITTED BY NAME –ABHIJIT NAYAK Roll no-1907101014 TOPIC- DISEASES OF PEAR SUBMITTED TO Respected Dr.Sangita Sahni ma’am Respected Dr. Phool Chand sir
- 2. Diseases of Pear Pear is one of the important fruit of temperate zone, this fruit is popular for its delicious taste. There are many diseases which badly affect this crop. Most severe of them are fire blight, powdery mil dew & crown gall of apple. Some of the major diseases are discussed here.
- 3. 1. Powdery mildew 2. Fire blight 3. Pacific Coast Pear Rust 4.Fabraea Leaf Spot 5.Phytopthora Crown Rot, Collar Rot and Root Rot 6.Pear –decline 7.Pear scab 8.Crown gall of pear LIST OF PEAR DISEASES
- 4. 1.POWDERY MILDEW Casual organism- Podosphaera leucotricha Symptoms – • On leaves- whitish powdery growth on upper & lower side comprising of oidea • On stem- whitish powdery growth • On fruits- whitish powdery growth but in dry condition Etiology- • Mycelia –septate, subepidermal houstiria • Asexual spore-conidia • Asexual fruiting body- oidium • Sexual spore- ascospore • Sexual fruiting body- cleistothecium • Primary source of inoculum: dormant mycelia in infected dormant bud • Secondary source of inoculum- barrel shaped conidia Epidemiology- • Warm weather condition • Temperature- 28-32 ‘c • Relative humadity- 80-90 % • Intermittent rainfall
- 5. Lifecycle: Management- Cultural- pruning of canker affected part & paste CoC at cut end Spray 5% urea on fallen leave Use of drip irrigation Chemical- Calcium oxychloride 0.3% Bordeux mixture 1% Streptocyclin 0.05% Biological- Erwinia herbicola • Psuedomonas fluorescens POWDERY MILDEW
- 6. Causal organism- Erwinia amylovora Symptoms: Affected parts appear to be scorched by fire. A watery ooze may be exuded from infected plant parts. The disease may kill entire trees. Fruit which are infected early remain small and appear shriveled, dark, and ‘water soaked’. They will remain attached to the cluster. Etiology: • Primary source of inoculum: Bacterial cells present on affected cankers and on cracks and crevices. • Secondary source of inoculum: Rain splash borne bacterial cells. Dissemination: Disseminated by bees and other pollinating insects and by rain. Disease cycle: The bacteria over winter in bark tissues along the edges of cankers caused by infection in previous years. The bacteria multiplies in the spring, the cankers exude a characteristic ooze, and the bacteria are disseminated by rain and insects to vulnerable tissues - especially open blossoms, tender vegetative shoot tips, and young leaves. The bacteria penetrate the tree at natural openings or wounds. Secondary infection arises from ooze from fresh infections. FIRE BLIGHT
- 7. Management Options: Control of fire blight is aimed at reducing the level of inoculum in the orchard, reducing the susceptibility of the trees through horticultural practices, and preventing infection at critical and times through the use of bactericides. Cultural Practices: Reducing primary inoculum by removing infected plant material when winter pruning. Inspecting orchard weekly during the growing season remove infected plant material. When removing infected plant material, cutting infected branches at least 12 – 18 inches below the lowest evidence Of disease. When removing infected plant material during the growing season, prune only on Sunny, hot days when rain is not predicted. Controlling insect vectors in the orchard. When planting new orchards, avoiding susceptible cultivars. Planting well-drained soil. Maintaining proper orchard nutrition in order to discourage excessive tree vigor. Chemical: COC (0.3%) and STREPTOCYCLIN (0.05%) Fire Blight
- 8. Casual organism-: Gymnosporangium libocedri Symptoms: Leaf: Spots fade and darken as the leaf matures or falls off the tree. Green shoots and leaves also are attacked but not as frequently. Fruit: Pear fruit are malformed while young and drop from the tree. Bright yellowish to orangish spots with numerous cup-shape pustules (aecia) develop over the fruit surface. Oriental and European cultivars are susceptible. ‘Winter Nelis’ is severely affected, but ‘Bartlett’ is not. Dissemination : Spores produced on eastern red cedar are discharged following rain, and disseminated by wind currents to pear hosts. Spores produced on pear may also be carried by wind to cedars. Primary source of inoculum: telial galls on cedar plant becoming air borne basidiopsores. Secondary source of inoculum: airborne basidiospores 3.PACIFIC COAST PEAR RUST
- 9. Cultural control: Remove alternate hosts around the orchard. The grower should be most concerned aut cedar pear rust if the cultivars grown in the orchard are susceptible to the disease, if there are eastern red cedars in the vicinity, and if there are numerous rainy periods during the spring. Cultural Management Options: Sources of infection may be reduced by cutting down nearby eastern red cedar, but it is difficult to entirely eliminate sources of infection due to the distance spores are able to be carried by the wind. Some pear cultivars are resistant to cedar pear rust, and may be grown without fungicide sprays to control it. Chemical: Certain scab fungicides may also control cedar pear rust mancozeb 2 ml per lit. Pacific coast pear rust
- 10. Casual organism- Fabraea maculata Symptoms: Leaf :spot can be found on petioles, leaves, shoots and fruits. Initial lesions on leaves are tiny, round, purplish-black spots, which quickly enlarge to 1/8 to 1/4 inch in diameter and usually have a blackish-brown center. Spots coalesce and severely infected leaves fall to the ground prematurely. A small black acervulus may develop in the center of each lesion, from which conidia ooze in a creamy, white mass in wet weather. Fruit :lesions are larger than those on leaves and cause the fruit to crack and drop. Lesions on current season's shoots may be observed as small inconspicuous, purplish- black spots. Some lesions develop into superficial cankers, but most are walled-off during the next growing season, so that cankers rarely persist in two-year-old wood. 4.FABRAEA LEAF SPOT
- 11. Disease Cycle: The four-celled conidia (Entomosporium maculatum), with a distinctive insect-like appearance, are spread mainly from overwintering leaf litter, and some from twig cankers, by splashing water from rains or overhead irrigation. Wetting periods for infection may vary from 8 to 12 hours at temperatures of 50 to 77 F (10-25 C). Lesions begin to appear about 7 days after the beginning of an infection period. The disease may advance rapidly in late summer as wind and rain distribute the conidia throughout the tree. Susceptibility of leaves and fruit to infection does not decrease with maturity. Nearly all pears of European descent are susceptible to this leaf spot. Management: This disease is controlled with applications of protectant fungicides. Early-season spray programs for pear scab should also control early-season leaf spot infections. Where ascospores and conidia of the fungus occur after petal fall, summer fungicide treatments are needed. FABRAEA LEAF SPOT
- 12. (Collar rot affects the scion portion of the tree, crown rot affects the rootstock portion of the tree. Root rot affects the root system away from the crown region.) Disease causing organisms: Phytopthora spp. Symptoms:Cankers may be seen at or below the ground line, and may extend from the original site Of infection into the root system and up the trunk to the bud union and above the bud union if the scion is also susceptible. Infected bark is brown and often slimy when wet. When the bark is pulled away, the cambium and phloem will be an orange, reddish brown color. The cankers caused by the fungus girdle the tree, resulting in poor vegetative growth and chlorotic foliage that may turn purple in the autumn. A severely infected tree may die. Dissemination: Soil born fungal pathogen. Pathogen survives in soil for several years as spores, especially in old orchard soils. May also be brought into the orchard on infected nursery stock. Disease cycle: The fungus survives in the soil as thick-walled spores (oospores) that are resistant to drought and relatively resistant to chemical treatment. The fungus may also be brought in on infected nursery stock and in contaminated irrigation water. Mobile spores (zoospores) originating from the oospores move to the tree and colonize the pear bark tissue. The fungus may build up to high in the soil in a short period under favorable conditions - i.e. during wet, cool periods after harvest and in spring. 5. Phytopthora Crown Rot, Collar Rot and Root Rot
- 13. Monitoring and Management: Key times for management: The best time to manage Phytopthora diseases is during the initial stages of orchard establishment, when selecting the orchard site, planting, site preparation and rootstock selection. Management Options: While there are some fungicides registered for control of Phytopthora, management is best achieved through cultural methods. Cultural Controls: Primary control of Phytopthora diseases is culture. When planting a new orchard, select the site and rootstocks carefully. Be sure the orchard site has adequate drainage throughout the year. When irrigating the orchard, do not saturate the soil for prolonged period is. Use rootstocks resistant to infection by the disease. Scion cultivars may also be chosen for resistance. Chemical:Bordeaux mixture 1% or Copper oxychloride (.03%) or Mancozeb 0.25% Phytopthora Crown Rot, Collar Rot and Root Rot
- 14. Casual organism:- Phytoplasma like organism Symptoms: Pear decline is characterized by two phases: quick decline and slow decline.Trees may wilt, scorch, and die in a few weeks or lose vigor over several seasons during which foliage gets sparse with little or no terminal growth and leaf size is reduced. An abnormal early red leaf coloration has been observed frequently on affected trees. Examining graft union reveals a brown line on the cambial face of the phloem tissue. Early or premature foliar discoloration is a general symptoms of this disease. Cultural control: 1. Use resistant or tolerant rootstocks. 2. Use the best orchard management practices, including the best possible insect and disease control, irrigation, drainage, fertilization, and pruning. 3. Control pear psylla. 4. When grafting Asian pear trees over to European (P. communis) cultivars, graft below the union of the Asian pear with its rootstock to avoid creating a highly decline-susceptible tree. 6.Pear decline
- 15. Casual organism-: Venturia pirina Symptoms: In spring, sooty spots with a soft velvet look appear on young fruit, stems, calyx lobes, or flower petals. fruit :Young infected fruit frequently drops or is misshapen. Scab spots expand with growth until halted by dry weather or sprays. Old fruit infections often crack open. Cracks are surrounded by russeted, corky tissue and then an olive-color ring of active fungus growth. If fruit is infected late in the season, about 2 weeks before harvest, pinpoint scab spots often show up in storage a month or more later. On leaves: olive-black spots expand with leaf growth but often cause the leaf to twist abnormally. Infected twigs show small blisterlike infections the size of a pinhead and develop a corky layer. Many twig infections are sloughed off during the summer season. 7.Pear scab
- 16. Etiology • mycelia –septate, subepidermal houstiria • Asexual spore- spilocea type of conidia • Asexual fruiting body • Sexual spore- ascospore • Sexual fruiting body- psuedothecium • Primary source of inoculum; pathogen survive on affected fallen leaves • Secondary source of inoculum; Airborne conidia Disease cycle : Peae scab
- 17. Cultural control: 1. Carefully discing to cover old leaves with soil, where practical, may help reduce spring infections. 2. Pruning out infected twigs also offers some benefit. 3. Applying dolomitic lime after leaf drop in fall to increase soil pH also helps reduce inoculum the next spring. Chemical control: spray schedule- Spray- silver tip to green stage mancozeb @ 2g/l or chlorothalonil @ 2g/l Spray –pink to blooming stage carbendazim @ 1.5g/l Spray- young fruit coc @ 3g/l Spray – maturation stage mancozeb @ 2g/l Spray –postharvest benomyl @ 1g/l Biological control: • Tricoderma species • Althelia species • Chaetomium species Pear scab
- 18. Causal organism: Agrobacterium tumefaciens Symptoms The disease first appears as small overgrowths or galls on the roots, crown, trunk or canes. Galls usually develop on the crown or trunk of the plant near the soil line or on underground roots. Above ground or aerial galls may form on canes of brambles of highly susceptible cultivars of pear. Aerial galls are not common on fruit trees. Below ground symptoms In early stages of development galls appear as tu¬mor-like swellings that are more or less spherical, white or flesh-colored, rough, spongy (soft) and wart-like. They usually form in late spring or early summer in each season. As galls age, they become dark brown to black, hard, rough, and woody. Some disintegrate with time while others may remain till the life of the plant. Above ground symptoms The tops of infected plants may appear normal. In severe infection, plants may be stunted; produce dry, poorly-developed fruits, or show various deficiency symptoms due to impaired uptake and transportation of nutrients and water. Causal OrganismThe crown gall bacterium is soil-borne and persists for a long time in the soil in plant debris. It requires a fresh wound to enter and infect and initiate gall formation. 8.Crown gall of pear
- 19. Infection process:- Wounds that commonly serve as infection sites are those made during pruning, machinery operations, freezing injury, growth cracks, soil insects, and any other factor that causes injury to plant tissues. Bacteria are abundant in the outer portions of primary galls, which is often sloughed off into the soil. In addition to primary galls, secondary galls may also form around other wounds and on other portions of the plant in the absence of the bacterium. The bacteria overwinter inside the plant (systemically) in galls, or in the soil. When they come in contact with wounded tissue of a susceptible host, they enter the plant and induce gall formation, thus completing the disease cycle. The bacteria are most commonly introduced into a planting site on or in planting material. Control 1. Obtain clean (disease free) nursery stock from a reputable nursery and inspect the roots and crowns yourself to make sure they are free from galls. Avoid planting clean material in sites previously infested with the bacteria. 2. Avoid all unnecessary root, crown, and trunk wounding by careless cultivation and other machinery operation, and control soil insects. Any practice that reduces wounding is highly beneficial. Preventing winter injury (especially on pears) is also beneficial. 3. On pears, the double trunk system of training may be a useful system for minimizing losses due to crown gall. If one trunk is infected, it can be removed. The remaining trunk can be pruned leaving a full number of buds until the second trunk can be renewed. Galls on the upper parts of the trunk or on canes can be removed by pruning. 4. A relatively new biological control agent for crown gall is available for pear, pear, stone fruit, blueberry, brambles, and many ornamentals. 5. The agent is a nonpathogenic strain of bacterium (Agrobacterium radiobactor strain K - 84) that protects the plants against infection by the natural presence in the soil. Crown gall of pear
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