A turf sample has something white covering the top of the leaf blades. Observing the diseased tissue under the dissecting microscope you see septate mycelium on the leaf. Looking in the leaf litter you find a hard flask-shaped structure that looks like a perithecium that is filled with ascospores. What class of fungi have you isolated?
Ascomycete
A blight of ornamentals is widely distributed disease of vegetables, ornamentals, and fruits. It is often a secondary soft rot of fruits and vegetables in storage. The noticeable sign of this disease is a gray fuzzy mycelium on the tissue. Often branched conidiophores with one-celled conidia are visible. Control in the greenhouse includes proper aeration, humidity reductions, and removal of infected tissues. Fungicides are partially successful in the field.
Gray Mold
Botrytis cinerea
This disease is economic on apples, pears, and hardwood. Cankers develop around the bud scars and in crotches of limbs. Bright colored perithecia are produced in spring near the cankers with conidia on conidiophores produced during summer. Control is by sanitation requiring removal and burning of cankers. Fungicides are available for fall application.
Nectria Canker of trees
Nectria galligena/ Fusarium spp.
It is considered worldwide in occurrence and is economical on peaches, nectarines, and plums. It causes leaf, flower and fruit deformation of stone fruit trees. Leaves pucker and fruit are enlarged and deformed. Ascospores in naked asci are found in the puckered leaf tissue. Usually, a single fungicide spray in late fall or early spring will manage this disease. It is considered worldwide in occurrence and is economical on peaches, nectarines, and plums. It causes leaf, flower and fruit deformation of stone fruit trees. Leaves pucker and fruit are enlarged and deformed. Ascospores in naked asci are found in the puckered leaf tissue. Usually, a single fungicide spray in late fall or early spring will manage this disease.
Peach leaf curl
Taphrina deformans
Ascospores born in an ascus
Ascomycete
A sample of dying turf was submitted to the lab. After isolating the fungal agent on a sterile medium and observing a small section under the compound microscope you see an oospore and other fungal structures that look like antheridia and an oogonia. What class of fungi have you isolated?
Oomycete
A disease which penetrates the bark of stems of the American chestnut and developed cankers which are reddish-orange to yellow-green and covered with pycinidia and perithecia. Conidia ooze out as long orange curls in moist weather. New systemic fungicides are promising and two tolerant cultivars have been developed.
Chestnut blight
Cryphonectria parasitica
This is an important disease of roses reducing flower production and weakening the plant. Leaves can be entirely covered with a black fungus and leaves may fall prematurely with raised purple-red lesions on the 1st year canes. Acervuli with conidia are often found in on the leaf surface under moist conditions in the summer although toward the end of the winter ascospores develop on apothecia on the dead canes. Although resistant varieties are available fungicides are usually required at weekly applications to manage the disease.
Black spot of rose
Diplocarpon rosae and Marssonina spp.
Causes diseases on plants by simply growing externally on the surface of the leaves without parasitizing the plant. It is common on turf grass, strawberries, vegetables and small ornamentals when the weather is warm and after rains. Signs include distinct crusty gray fruiting structures or sporangia of the plant leaf surface.
Slime mold
Fuligo, Mucilage, or Physarum
Conidia born on conidiaphores
Deuteromycete
You have a diseased cabbage leaf with a necrotic circular lesion on the leaf. Observing the diseased tissue under the dissecting microscope you see mycelium at the center of the lesions. Placing some of the mycelia on a glass slide under the compound microscope you see cross walls in the mycelium and conidia in chains on conidiophores. What class of fungi have you isolated?
Deuteromycete - imperfect stage
This disease is usually seen in monoculture conditions when soil moisture is at least 50% of field capacity and temperatures are unfavorable for the host plant. Symptoms of pre and post-emergence damping off with root and hypocotyl water-soaked lesions are descriptive of this disease. Signs can include a white mycelium with zoosporangiophores present on the surface of the leaves and an oogonium found in the leaf tissue. Excessive nitrogen is usually associated with the disease which directly penetrates the plant. Management includes soil sterilization, planting resistant varieties, crop rotation, good drainage, air circulation between plants and chemical seed treatments.
Seedling disease
Pythium ultimum
This soybean disease which kills full-grown plants at mid-season. Symptoms include interveinal chlorosis of the leaves with dark brown cankers on the plant stalk. Pycnidia are formed in summer producing alpha and beta conidia and or perithecia with ascospores in late winter or early spring can be found in the diseased tissue. It is spread on infested seed and is latent in the plant until flowering. Resistant varieties are available.
Stem canker
Diaporthe phaseolorum var. caulivora
This disease is caused by an endoparasitic slime mold. It lives off the host cell and stimulated the host cells to enlarge and divide making more nutrients available to the pathogen. Control by crop rotation, healthy transplants, and proper soil pH.
Club root of crucifers
Plasmodiophora brassicae
zoospores born in sporangia
Oomycete
You have a diseased bell pepper with a necrotic circular lesion. Observing the diseased tissue under the dissecting microscope you see mycelium and small structures at the center of the lesions. Placing some of the mycelia on a glass slide under the compound microscope you see cross walls in the mycelium. The structures look like pycnidia and one-celled conidia are oozing out. What class of fungi have you isolated?
Deuteromycete
This fungal disease attacks stone fruits and can cause 50-75% losses. Symptoms first appear on blossoms in humid weather. On fruit small circular brown spots spread and fruit mummify. Mummified fruit on the ground produces apothecia for the next spring. Control included fungicide sprays with bloom and several weeks before harvest.
Brown rot of fruits
Monilia fructicola and Monilinia fructicola
This is a common disease on cereals and wild grasses. The fungus infects the ovaries and replaces the seed with a hard mass of fungal mycelium called sclerotia. The sclerotia are poisonous to humans and animals. Control depends entirely on using clean seed, although deep plowing and crop rotations help eliminate the disease.
Ergot of cereals
Claviceps purpurea
This plant disease occurs is common on cereals and grasses and occurs worldwide. The disease is favored by warm temperatures and humid weather when the conidia are produced on conidiophores. The widespread epidemic of race T occurred in 1970 with the extensive utilization of the Texas cytoplasm male sterility gene. This fungus is saprophyte in soil and management includes resistant hybrids, disease-free seed, fungicides and crop rotation.
Southern corn leaf blight
Cochliobolus heterostrophus - Bipolaris maydis
sporangiaspores born in sporangium
Zygomycete
A diseased tomato seedling with a water-soaked lesion on the root and hypocotyl. Observing the diseased tissue under the dissecting microscope and at the edge of the lesion is mycelium. Placing some of the root hypocotyl with the mycelium on a glass slide under the compound microscope you see no cross walls or septation in the mycelium. This characteristic narrows the scope of possible fungi classes you have isolated. What are the possible classes?
Zygomycete or Oomycete
Very destructive and widespread diseases which attack trees, vegetables, flowers, crops, and ornamentals. Common in warm climates, sandy soils of the southern US and is known to kill entire fields. Most serious when temperatures are high all season. Mature reproductive plants are attacked with the leaves losing turgidity, wilting, turning brown and dying but remaining attached to the plant. Characteristically symptoms will appear on one side of the stem upward and the vascular bundles of the upper root and lower stem are discolored. Control is achieved by resistant varieties in the field and soil sterilization in the greenhouse.
Vascular wilt of tomato
Fusarium oxysporum f. sp. lycopersici
This disease attacks a wild range of plants from turf, vegetables, and flowers to field crops and can cause disease at any stage of plant growth. Incidence is worldwide. Signs of the disease are distinctive with white fluffy mycelium covering the plant tissue under high moisture conditions. The fungus produces sclerotia 0.5 to 1 mm in diameter which are known to survive for up to 3 years in the soil. Control is by resistant cultivars, fungicides, and sterilization in the greenhouse with good aeration.
Cottony rot or white mold
Sclerotinia sclerotiorum
This blight is found in all areas of the world were potatoes and tomatoes are grown. It can cause total destruction of the plant within 2 weeks when weather conditions are cool and humid. Symptoms include water-soaked lesions with chlorotic borders expand rapidly on leaves. Signs are a white sporulation on the bottom of the leaves at the leading lesion edge. Zoosporangiophores and an oogonium are visible when looking at the diseased tissue under the microscope. Control is most often achieved in the field by resistant varieties, crop rotation, and fungicides. Control is obtained through IPM with sanitary measures, resistant varieties, crop rotation, planting healthy seedlings; irrigation timing to reduce the dew period, split applications of fertilizer and well-timed chemical sprays.
Late blight
Phytophthora infestans
cenocytic mycelium
Zygomycete or Oomycete