 |
|
 |
|
 |
|
       |
Verticillium Wilt - Verticillium spp.
   HOSTS: Ash, elm, sumac, linden, maple, raspberry and
occasionally fruit
trees; vegetable crops, especially solanaceous crops (eggplant, pepper, potato, tomato). DESCRIPTION:
Foliar
symptoms typically include wilting, curling, yellowing, marginal or
interveinal browning and death. Often these symptoms may look like water
stress and can occur on only one side of the plant. On woody plants, symptoms may
include dieback of branches or a portion of the plant. Also,
wood under the bark may exhibit discolored streaks or bands. The color
of the streaks can range from light tan to grayish olive to
brownish-black. Yellowing and defoliation often progress from the bottum to the top of the plants. LIFE
CYCLE: Verticillium wilt is caused by a soil inhabiting fungus which affects the plant's
vascular system. Infection occurs through the roots or where damage to
the stem has occurred near the soil line. Once the fungus invades the
plant, it spreads into the water-conducting tissues (xylem) disrupting
water movement and normal plant functions. The pathogen survives in
plant debris, in roots and trunks of killed trees for several years and
as a resting structure (microsclerotia) can persist in the soil for
years. Water-stressed or wounded trees are most susceptible. Wet, warm
(65-72° F.) weather encourages this fungus. CONTROLS:
There is no
cure for Verticillium. Use resistant cultivars or species. Conifers, birch, and dogwood are not susceptible. Keep woody
species well-watered. High nitrogen fertilizers can increase wilt
severity. Remove and destroy infected plants. Prune and destroy affected tree branches before leaves fall. Preventative: For vegetables, soak seeds in hot water or a 0.5% bleach solution before planting. Cultural: In the case of vegetable crops, do not plant out transplants until soil temperatures are 65-70° F. Rotate your crops on a 4 - 5 year basis with non-susceptible plants such as sweet corn, spinach, beans, and peas. DESTROY infected plants Soil solarization for 4 – 6 weeks in July and August may help. For woody plants: Mulch with 1 – 3” of low pH compost. |
|
|
|
 |
|