Lecture 16 Turf, Flower and Vegetable Diseases

Turf diseases Turf diseases Fusarium patch, red thread disease, fairy rings and thatch are common in Seattle

Flower diseases Azalea – leaf and flower gall Camellia – cold damage Cherry – brown rot, Botrytis Geranium – Botrytis blight Lilac – Botrytis flower blight Narcissus – chocolate spots? Pansy – Botrytis blight Petunia – Botrytis blight Rhododendron – flower bud damage (frost) Rose – everything Tulip –fire – Botrytis, virus

Botrytis (Grey mold) Rose Cherry

Roses have earned the reputation of one of the most susceptible plants to diseases and pests; chemical fungicides and pesticides are widely used both by growers and home gardeners…… Some growers now raise roses organically without chemicals, e.g.,

A listing of known diseases that affect roses Described Rose Diseases *Rose Anthracnose *Rose Bacterial Blight *Rose Black Spot *Rose Botrytis Blight *Rose Cankers *Rose Crown Gall *Rose Downy Mildew *Rose Hairy Root *Rose Leaf Spots *Rose Powdery Mildew *Rose Rust *Rose Spring Dwarf *Rose Mosaic Virus Believe it or not, there’s more!!

Rose Diseases and Common Methods for Control Powdery Mildew (Sphaerotheca pannosa) Overwinters in infected buds, canes and fallen leaves and attacks young spring growth. Thrives in areas with high relative humidity at night when temperatures are around 60 degrees F. Also thrives at around 80 degrees F with 40%-70% RH. Best way to prevent powdery mildew and other diseases without using chemicals! Clean up fallen leaves, deadheads and other debris. DO NOT COMPOST! Allow adequate space for plants when planting to ensure good air circulation. Avoid overwatering, overhead watering, and applying too much fertilizer. Plant “resistant” varieties

Blackspot (Diplocarpon rosae) Infects foliage and stems causing defoliation and weakens plant. Presence of water on plant surface for 7-8 hours is needed for infection.

Other Diseases Rose Rust Phragmidium ssp. Botrytis Blight Botrytis cinerea Crown Gall Angrobacterium tumefaciens

Common Diseases of the Home Vegetable Garden

Carrot - Root Knot Nematode Meliodogyne spp. Microscopic, live in soil Feed on roots Distortion of roots Stunted roots, short bushy root hairs Yellow or stunted leaves

Crucifers Black Rot Xanthomonas campestris Bacteria Enters through wounds on leaves Leaves yellow and die in “V” shaped pattern from margin to midrib Leaf Drop Spreads through xylem to other parts of plant

Blossom End Rot Symptoms: First appears as a brown discoloration at blossom end of fruit. Spot enlarges and darkens, eventually becoming sunken and leathery. Soft Rotting may occur if secondary fungi or bacteria invade the spot.

Lettuce Bacterial Soft Rot Symptoms Rotting of the edges of lower leaves Leaves of the head finally dissolve into an unappetizing, slimy rot.

White mold Sclerotinia rot A fungal disease which may attack the stems, leaves, and pods of beans.

Signs: Purple to brown scabby areas or warty lesions on the surface of the tuber. Small galls and warts may form on roots of some potatoes. Potatoes Powdery Scab is caused by a fungus, Spongospora subterranea, that is carried on the seed and can survive 3 to 10 years in the soil.

Corn Smut A fungus (basidiomycete), Ustilago zeae, overwinters in soil as teliospores, that may survive 2 or 3 years. Spores may be wind blown long distances.