Development of disease

1. Development of disease • Overwinter: ascospore, thick walled • Conidia • 1st inoculum : ascospore • Penetration : directly through cuticle or through stoma • Habit: intercellular between cuticle and epidermis • Habitat : biotrophs • Dissemination : by wind • Interest : complicated (by budding of ascospore and conidia) • More susceptible period : low temp, high humidity; • Older plant is more resistance than young one

3. Control • Fungicide spray late fall or early springs Bordeaux mixture. • Chlorothalonil applied twice (Late fall and early spring).

4. Diseases caused by chytridiomycota Chytrids lack true mycelium round or irrigular shaped thallus cell wall: chitin, maturation thick-walled resting spore or sporangia.

5. Local spread of disease depends on moisture. • Synchytrium &physoderma do not kill host but stimulate it to divide. • Overwinter as resting spore in soil or spherical,irrigular shaped thallus in host tissue. • Resting spore gives zoospore –cyst-2ry zoospore.

6. Soil- water inhabiting Olpidium: root disease of many kinds. Synchytrium: Black wart of potato. Physoderma. P. alfalfae : crown wart of alfalfa. P. maydis: brown spot disease of corn.

8. Olpidium is a vector for six plant virus : TNV (Tobacco necrtrotic virus), lettuce big vein virus

11. Disease caused by zygomycota Mycelium without cross walls- non motile spore- sporangia. resting spore=(2 similar morphological units). Terrestrial fungi-spore floating around in air Saprophytic, weak parasite cause soft rot or molds. Rhizopus are opportunistic pathogen human.

12. Three genera cause disease to plants • Choanephora: soft rot of floral part ,fruit squash, pumkin, peper, okra. • Rhizopus common bread mold fungi. • Mucor soft root corms ,bulbs, veg flower ,seed It colonizes the tissues which it killed by growing and enzyme secreting. • Endomycorrhizae Glomus, Endogone, associated with root benificial plant.

13. Rhizopus causes Soft root of fruit and fleshly organ Hull rot of maturing almond Head rot of some flower During harvesting, storage, transit, marketing e.g. sweet potato, strawberry, peaches, flowers…..

15. Symptoms • Water soaked area ,very soft. If skin of organ intact loss water mummy. • Exuding liquid- bushy growth on surface. • Give off a mildly pleasant smell. • yeast & bacteria sour odor. • Loss of moisture dry mummify. • Loss of moisture slow break down & disintegrate in a leaky water rot.

16. Development of disease • Growth pectinolytic enzymes. • dissolves pectin in middle lamella Loss cohesion soft rot. cellulytic enzumes degredation of cellulose.

17. Rhizopus lives more like a saprophyte than a parasite. • Factors help to develop disease are humidity, temp and insufficient maturity. • When food supply diminsh, fungus form zygospores (resting spore). • Plant form cork layer to inhibit more fungal growth.

19. Control • Avoid wounding. clean containers CuSO4, formaldehyde, S-fume, chlorpicrin. Storage: Temp. below 10 c for strawberry, 25-30C & 90% hum. 10-14 days(to form cork layer. Biocontrol: Candida, Pichia.

20. FOLIAR DISEASES CAUSED BY ASCOMYCETES AND DEUTEROMYCETES (MITOSPORIC FUNGI)

21. Ascomycota • Some of the most common Ascomycetes causing primarily foliar diseases include the following: • -Cochliobolus, several species of which cause leaf spots, blights and root • rots on most cereals and grasses. • -Blumeriella (Higginsia), causing leaf spot or shot hole of cherries and • plums. • Magnaporthe, M. grisea causing the rice blast disease and gray leaf spot • of other cereals and of turf grasses. • Microcyclus, M.ulei causing South American leaf blight of rubber. • - Dothistroma, D. pini causing needle blight of pines Elytroderma • deformans, causing a leaf spot and witches'-broom of pines • - Lirula, causing needle blight of spruce Lophodermium seditiosum,

22. Deuteromycota • Some of the most common mitosporic fungi causing primarily foliar but also other symptoms on a large variety of host plants are Alternaria, Ascochyta,Cercospora, Cladosporium, Phyllosticta, Pyricularia,Septoria, and Stemphylium. Many others are less common

23. Similarity • The foliar spots and blights causedby imperfect fungi on numerous hosts and are quite diverse. • The disease cycles and controls of these diseases are quite similar, however. Nevertheless, considerable variability may exist among diseases on different hosts, or when the diseases develop under different environmental conditions

24. Dissemination • It spread to other plants by wind, wind-blown rain, water, and insects and cause more infections .

25. Overwinter • In most cases, these fungi overwinter primarily as conidia or mycelium in fallen leaves or other plant debris. • Some, however, can overwinter as conidia or mycelium in or on seed of infected plants or as conidia in the soil. • When perennial plants are infected, the pathogens may overwinter as mycelium in infected tissues of the plant. • When these fungi are carried with the seed of annual plants, damping-off of seedlings may develop.

26. Control of such diseases is accomplished primarily by using resistant varieties and employing fungicidal sprays or seed treatments. In some diseases, however, use of disease-free seed, removal and destruction of contaminated debris, or both may be most important. Control

27. ALTERNARIA DISEASES • Alternaria diseases : as leaf spots and blights. • damping-off of seedlings, stem rots, and tuber and fruit rots • early blight of potato and tomato, leaf spot and fruit spot on cucurbits and onions and on apple and citrus, fruit rot on cherry and sour cherry, core rot of apple, and rot of lemons and oranges.

29. Symptoms • The leaf spots are generally dark brown to black, often numerous and enlarging, and usually developing in concentric rings, which give the spots a target-like appearance. • Lower, senescent leaves are usually attacked first, but the disease progresses upward and makes affected leaves turn yellowish, become senescent, and either dry up and droop or fall off.

30. Symptoms of stem • Dark sunken spots develop on branches and stems of plants such as tomato. • Stem lesions developing on seedlings may form cankers, which may enlarge, girdle the stem, and kill the plant. • In belowground parts, such as potato tubers, dark, slightly sunken lesions develop that may be up to 2 centimeters in diameter and 5 to 6 millimeters in depth.

31. Symtoms of fruits • Alternaria may attack fruits when they approach maturity in some hosts at the blossom end . • The spots may be small and sunken or may enlarge to cover most of the fruit, and they may be leathery and have a black, velvety surface layer of fungus growth and spores.

32. Development of Disease

33. Overwinter • Overwinter :as mycelium or spores in infected plant debris and in or on seeds. • If the fungus is carried with the seed, it may attack the seedling, usually after emergence, and cause damping-off or stem lesions and collar rot.

34. The PathogenAlternaria spp

35. Penetration & dissemination • The germinating spores penetrate susceptible tissue directly or through wounds • and soon produce new conidia that are further spread by wind, splashing rain, etc. • With few exceptions, Alternaria diseases are more prevalent in older, senescing tissues, particularly on plants growing poorly because of some kind of stress.

36. Habit • infect Actually, many species of Alternaria are mostly saprophytic, i.e., they cannot living plant tissues but grow only on dead or decaying plant tissues and, almost, on senescent or old tissues such as old petals, old leaves, and ripe fruit. • Therefore, it is often difficult to decide whether an Alternaria fungus found on diseased tissue is the cause of the disease or a secondary contaminant.

37. Control • Adequate nitrogen fertilizer generally reduces the rate of infection by Alternaria. • Alternaria diseases are controlled primarily through the use of resistant varieties, disease-free or treated seed, and chemical sprays with appropriate fungicides. • Crop rotation, removal and burning of plant debris, if infected, and eradication of weed hosts help reduce the inoculum for subsequent plantings of susceptible crops.

38. Biocontrol&UV • Several mycoparasitic fungi are known to parasitize various species of Alternaria, but so far none has been developed into an effective biological control of the pathogen. • In the greenhouse, infections by UV at least some Alternaria species can be reduced drastically by covering the greenhouse with special UV light-absorbing film, as filtering out light inhibits spore formation by these fungi.

39. VASCULAR WILTS CAUSED • BY ASCOMYCETES AND • DEUTEROMYCETES • (MITOSPORIC FUNGI)

40. Vascular Wilt • Vascular wilts are widespread, very destructive, spectacular, and frightening plant diseases. • They appear as more or less rapid wilting, browning, and dying leaves and succulent shoots of plants followed by death of the whole plant. • Wilts occur as a result of the presence and activities of the pathogen in the xylem vessels of the plant. • Entire plants may die within a matter of weeks, although in perennials, death may not occur until several months or years after infection.

41. Common Genera • There are four genera of fungi that cause vascular wilts: Ceratocystis, Ophiostoma, Fusarium, and Verticillium. Each of them causes disease on several important crop, forest, and ornamental plants. • Ceratocystis causes the vascular wilt of oak • Ophiostoma causes the vascular wilt of elm trees, known as Dutch elm disease (O. novo-ulmi).

42. Fusarium spp • Fusarium causes vascular wilts of vegetables and flowers, herbaceous perennial ornamentals, plantation crops, and the mimosa tree (silk tree). • Most of the wilt-causing Fusarium fungi belong to the species Fusarium oxysporum.

43. Specificity • Different host plants are attacked by special forms or races of the fungus. The fungus that attacks • tomato is designated F.oxysporumf. sp. Lycopersic; • cucurbits, F. oxysporum f. sp. conglutinans; • banana; F. oxysporum f. sp. cubense; • cotton, F. oxysporum f. sp. vasinfectum; • carnation, F. oxysporum f. sp. dianthii; and so on.

45. Verticillium spp • Verticillium causes vascular wilts of vegetables, flowers, field crops, perennial ornamentals, and fruit and forest trees. Two species, Verticillium albo-atrum, and V. dahliae, attack hundreds of kinds of plants, causing wilts and losses of varying severity.

46. Fusarium Wilts • Fusarial wilts are most severe under warm soil conditions and in greenhouses. • Most fusarial wilts have disease cycles and develop similar to those of the Fusarium wilt of tomato.

47. FUSARIUM WILT OF TOMATO • The disease causes great losses, especially on susceptible varieties and when soil and air temperatures are high . • Infected plants become stunted and soon wilt and finally die. • Occasionally, entire fields of tomatoes are killed or damaged severely before a crop can be harvested.

48. Symptoms • The first symptoms appear as slight vein clearing on the outer, younger leaflets • . Subsequently, the older leaves show epinasty caused by drooping of the petioles. • . • . It followed by stunting of the plants, yellowing of the lower leaves, occasional formation of adventitious roots, wilting of leaves and young stems, defoliation, marginal necrosis of the remaining leaves, and finally death of the plant.

49. Internal symptoms • A combination of the processes of vessel clogging by mycelium, spores, gels, gums, and tyloses and crushing of the vessels by proliferating adjacent parenchyma cells, is responsible for the breakdown of the water economy of the infected plant. • When the leaves transpire more water than the roots and stem can transport to them, the stomata close and the leaves wilt and finally die, followed by death of the rest of the plant. • The fungus then invades all tissues of the plant extensively, reaches the surface of the dead plant, and there sporulates profusely.

50. The PathogenFusarium oxysporum f. sp. lycopersici.