Extensive Powdery Mildew - Ask Extension
I dealt with a lot of powdery mildew during this growing season. If affected my cucumbers in my organic vegetable garden, as well as the zinnias on bo...
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Extensive Powdery Mildew #890275
Asked November 25, 2024, 12:54 PM EST
I dealt with a lot of powdery mildew during this growing season. If affected my cucumbers in my organic vegetable garden, as well as the zinnias on both sides of my house. The leaves and stems were greatly affected and very unsightly. I also do not use any type of weed killer in my lawn, so there was a large area around my zinnias where the plantain and dandelions were also covered in powdery mildew. I removed the affected plants and debris near the end of the growing season when the powdery mildew was too unsightly. My question is - what do I need to do to my garden beds/soil to prevent any of the mildew spores from overwintering? Would it be productive to mulch my vegetable garden beds with dried leaves, or will that exacerbate the issue next year?
Macomb County Michigan
Expert Response
Erica,
Zinnias and cucumbers are often plagued by powdery mildew. You're off to a good start by removing the infected plant matter. You should also remove the underlying mulch so you can start the season off clean. Pay attention next summer, and control if needed if it begins early in the season. Many of the new varieties of zinnias are resistant to powdery mildew.
In addition, management and control of powdery mildew is accomplished with good cultural practices. Such practices involve increasing air circulation and light penetration by pruning and thinning plants to reduce overcrowding in the landscape.
Water inhibits spore germination for most powdery
mildews, so overhead watering of the leaves during the
day and when humidity is low greatly inhibits infection
and can protect the plant.
Powdery mildew seldom warrants chemical control
in the home landscape and is more often an issue of
nursery and greenhouse production. When addition
disease control in desired, materials with low
environmental impact, such as horticultural oils or neem
oil can prevent infection when applied to green tissue
on the plant. Such applications can remain effective for
7 to 14 days in the home landscape (depending upon plant growth and rainfall), but will likely require repeated
reapplication. Do not apply these products when temperatures are above 85°F.
Please take a look at the document at the link below for more information on powdery mildew and Table 2 for products labeled for control of powdery mildew, if needed.
LINK : bp-5-w.pdf
Thak you for using Ask Extension.
Pam
MSUE Master Gardener
Zinnias and cucumbers are often plagued by powdery mildew. You're off to a good start by removing the infected plant matter. You should also remove the underlying mulch so you can start the season off clean. Pay attention next summer, and control if needed if it begins early in the season. Many of the new varieties of zinnias are resistant to powdery mildew.
In addition, management and control of powdery mildew is accomplished with good cultural practices. Such practices involve increasing air circulation and light penetration by pruning and thinning plants to reduce overcrowding in the landscape.
Water inhibits spore germination for most powdery
mildews, so overhead watering of the leaves during the
day and when humidity is low greatly inhibits infection
and can protect the plant.
Powdery mildew seldom warrants chemical control
in the home landscape and is more often an issue of
nursery and greenhouse production. When addition
disease control in desired, materials with low
environmental impact, such as horticultural oils or neem
oil can prevent infection when applied to green tissue
on the plant. Such applications can remain effective for
7 to 14 days in the home landscape (depending upon plant growth and rainfall), but will likely require repeated
reapplication. Do not apply these products when temperatures are above 85°F.
Please take a look at the document at the link below for more information on powdery mildew and Table 2 for products labeled for control of powdery mildew, if needed.
LINK : bp-5-w.pdf
Thak you for using Ask Extension.
Pam
MSUE Master Gardener
