Plant Pathology Flashcards
Aster yellows
Phytoplasma bacterial disease, lives in the phloem; symptoms include chlorosis of young shoots, stiff bunchy growth, and/or greenish or dwarfed flowers. Spread by leafhopper insects. Prevented by 38-42 degree celsius temperatures for two to three weeks. Prevent by quickly removing all diseased plants to prevent spread. Members of the Asteraceae family are especially vulnerable.
Smut
Fungal disease, lives within blisters of seeds, leaves, stems, flower parts, and bulbs; symptoms include galls/boils affecting above ground structures, yellow striping on leaves, and/or powdery black or brown material coating the leaf. The powdery substance is reproductive pollen and will only occur in late stages. Wind dispersed disease, so it’s difficult to prevent. It’s simply recommended to grow more resistant plants and avoid nitrogen rich fertilizers.
What plants do aster yellows affect?
It affects over 300 species of plants and has a very diverse range. This range includes ornamental plants like asters, coneflowers, zinnias, marigolds, chrysanthemums, petunias, and snapdragons. It also includes edibles like lettuce, carrots, tomatoes, and celery. Grasses and grains can be affected. Plantains (herb), dandelions, and other broad-leafed weeds are also affected.
