| da devil made me do it 2006-01-21, 5:21 pm |
| http://hgic.clemson.edu/factsheets/HGIC2206.htm
POWDERY MILDEW
Powdery mildew causes a white powdery growth on the upper surfaces of leaves
and on the stems of infected plants. Infected areas are often stunted and
distorted and may drop prematurely from the plant. Fruits are usually not
directly affected, but their size and growth may be stunted. Powdery mildew
is caused by the fungi Erysiphe cichoracearum and Sphaerotheca fuliginea.
Infection can occur when temperatures are between 50 and 90 ° F, during dry
weather with high relative humidity. The disease can be a particular problem
on late-planted squash.
Prevention and Treatment: Powdery mildew-resistant varieties (Table 1) are
available for most cucurbits, thus with proper planning, chemical control
should not be necessary. Preventative fungicide treatments are available
(Table 2) if disease becomes severe enough to warrant chemical control.
DOWNY MILDEW
Downy mildew is one of the most important leaf diseases of cucurbits.
Typically, symptoms begin as small yellow areas on the upper leaf surface.
As lesions expand, they may become brown with irregular margins. Affected
areas may grow together, and the entire leaf may wither and die. Infected
plants also develop a gray mold on the lower leaf surface. The fruit is not
affected, but in the case of cantaloupes, it will be less sweet. This
disease is caused by the fungus Pseudoperonospora cubensis and is favored by
moist conditions.
Prevention and Treatment: Use varieties that are resistant to this disease
(Table 1). Fungicides are available for the home vegetable garden if disease
becomes severe enough to warrant chemical control (Table 2).
Downy mildew: chlorothalonil or maneb1 or mancozeb1 or fixed copper4
Powdery mildew:
sulfur2 or cholorothalonil or paraffinic oil + baking soda3
Downy mildew
chlorothalonil or maneb1 or mancozeb1 or fixed copper4
Powdery mildew sulfur2 or cholorothalonil or paraffinic oil + baking
soda3
"Charles" <lockhart@ifa.hawaii.edu> wrote in message
news:1137793550.828290.67630@g43g2000cwa.googlegroups.com...
> Some of my squash plants last year got kind of a while powdery mold on
> the leaves, and those leaves eventually died. It was kind of a race,
> the leaves closest to the root were dieing, while the plant produced
> new leaves at the other end. Eventually we lost. Anybody have that
> problem and know how to deal with it? The leaves just got covered with
> the mold, then dried up and died.
>
|