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Don’t Forget About Your Gardens in Late Summer

University of Minnesota Extension, Stearns County News
August 16, 2017        
Source:  Beth Berlin, Extension Educator-Horticulture
University of Minnesota Extension
Stearns, Benton, & Morrison Counties


Don’t Forget About Your Gardens in Late Summer
By Beth Berlin, University of Minnesota Extension

ST. CLOUD, Minn. (8/16/17) — You may have noticed a few tree’s leaves already hinting at their fall color and the back-to-school shopping is in full swing, that means summer is already wrapping up.  For gardeners it isn’t a time to take a break, there are several things we should keep in mind this time of the season.

Continue to monitor your vegetable and flower gardens.  If you notice an issue such as powdery mildew on your bee balm or fungal leaf spot on your iris. Make a plan to discard and do not put on your compost pile.  Most compost piles will not reached the required temperatures to kill off the issue. Be sure to clean your tools with a water-bleach solution before using on healthy plant material.

Continue to monitor for insects as well. The sap or picnic beetle which is often found in raspberries can also impact tomatoes, sweet corn, and melon. The picnic beetle is between 1/8-1/4 inch long, dark in color with pale orange spots on the wing covers. Typically they are found on overripe fruits or vegetables so it is critical to be prompt with your harvesting and removing any overripe produce from the area.  Insecticides are not typically necessary, focus on timely harvests to prevent damage to your crops.

Tomatoes and potatoes can suffer from late blight at this time of the year. Late blight is caused by the pathogen, Phytophthora infestans and appears on both potatoes and tomatoes; it can occur on other members of the Solanaceae family as well.

First symptoms include pale green, water-soaked spots typically on the tip of the leaves or edges. The lesions are often surrounded by a yellowish border, which then spread rapidly and cause the leaves to turn brown, shrivel, and die.  During periods of high humidity or moist conditions, white fungal growth may also occur on the underside of leaves. Stems may develop dark lesions throughout the plant. The fruit can develop spots that eventually become leathery and brown in color.  Late blight spreads rapidly and can devastate an entire crop within days. It can blow in from infected crops, be introduced from seed or transplants, volunteers or weeds.

Management of the disease is difficult because it spreads so quickly. Select resistant varieties, control volunteer tomato and potato plants as well as solanaceous weeds like nightshades. Inspect plants at least once a week, remove any symptomatic plant parts. Put affected plant material in a black plastic bag and leave in the hot sun, or dig a hole and bury it. Once disease is present, it can be impossible to control even if using fungicides. Be sure to read and follow all safety and application directions on the fungicide label.

Although this can be a busy time of year, don’t forget about your gardens, they still need your watchful eye. Neglecting them can lead to loss of produce or continued issues year after year.


PHOTO: Picnic Beetle. Photo credit: Tom Murray, University of Minnesota.


Beth Berlin
Extension Educator, Horticulture
(320) 255-6169
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