The Pesky Pest & Dreaded Disease Corner: Problems with Powdery Mildew
- Megen Toaldo, Sales Associate
it consistently does year after year, powdery mildew travels north with
the wind from the southern states and finds its way into your garden.
The warm days and cool nights of late summer provide an ideal
environment for the growth and spread of the spores that are responsible
for this disease. Caused by the fungus Podosphaera xanthii, powdery
mildew can affect just about any type of plant, and is easily recognized
by a powdery looking growth on upper and lower leaf surfaces. While
the effects are mild for many types of plants, others such as cucurbits,
onions, artichokes, apples, pears, and grapes can be damaged more
seriously, causing reduced yields and early death of the plant.
Fortunately, there are early measures that one can take to
prevent and control powdery mildew. Prevention is easy by using proper
plant spacing with good air circulation, along with choosing resistant
or tolerant varieties. Although – rest assured – there are several ways
to control an infestation should one occur. Spraying your plants with a
solution of baking soda and water (1 tsp: 1 qt) raises the Ph, which
creates an unfriendly environment for the fungus to grow. Another
solution (albeit one that we haven’t tried ourselves) was discovered by
Wagner Bettiol, a scientist from Brazil: spray your plants with a
combination of 1 part cow’s milk with 9 parts water. Along with
controlling the disease, it also acts as a foliar fertilizer, boosting
the plant’s immune system. While raw cow’s milk has proven to have the
best effects, it seems that any cow’s milk will do its part in helping
to control powdery mildew. Try using a sticker such as ThermX-70 or Crocker’s Fish Oil; otherwise both these applications will need to be repeated after rain.
Now that you are in the know, you can enjoy helping your
garden grow! Tune in next month for information about late blight in
tomatoes and potatoes.