For fungus on hydrangea, check moisture
Q. We have several types of hydrangeas without problems. However, the original Endless Summer seems to have fungus or another infection issue again this year. The area faces east but also gets a little afternoon sun from the south. How do you recommend we treat the plant to eliminate the infection or blight? — K. Credeur, Yorktown
A. In recent weeks I have fielded several hydrangea questions similar to yours. Unfortunately, hydrangea is host to a number of fungal pathogens that attack the foliage. This is usually an issue related to persistent rain and high humidity. Cercospora leaf spot is a common fungal disease that attacks hydrangea, as well as some other landscape plants. It typically begins as leaf spots or lesions on older leaves, then progresses up the plant. Luckily, it rarely kills its host, but in severe cases may completely defoliate it.
Over successive seasons of infection, plants will lose vigor and may eventually succumb to the pathogen. As with most fungal diseases, water management is key to control. Watch your irrigation practices and consider thinning your plant to facilitate good air circulation. Basic sanitation is very important. With minor infections, picking those leaves early will help limit new infections. Be sure to keep the dropped leaves raked up and removed from the site.
A number of products containing the fungicide chlorothalonil may help control the spread. Bonide Fung-onil, Ortho Max Disease Garden Control and Daconil are three products that fit the bill. Serenade, a bio-fungicide and various copper compounds have been used with some success on organic vegetable crops. Repeat applications are required to protect newly emerging leaves. And as always, read carefully and follow label instructions.
And a few more things
The last week or so, just as this time last year, I have received questions concerning the lack of tomato fruit set and ripening. Temperatures above 90 degrees (daytime) and 72 degrees (nighttime) can adversely influence flowering, pollination and fruit set — causing blossom drop and fruit abortion. We’ve experienced a few of those.
Researchers at the University of Delaware used shade cloth on tomatoes for two consecutive summers and found the yields of shaded plants were 32% (very hot year) and 12% to 15% (hot year) more productive over non-shaded plants of the same variety. Shaded plants had improved size and quality. Bonnie’s Plants recommends using 50% shade cloth and orienting it so that plants receive morning sun and are shaded in the afternoon.
Additionally, when temperatures hit the 90s, plants stop producing lycopenes, the red pigments, and ripening may stop altogether. Bonnie’s recommends picking those partially ripened fruits and letting them finish ripening indoors.
Reminders: I ask you to write in and share this year’s success (or failure) with tomatoes and your garden in general. Try something new, different, or for the first time? Let me hear about it.
The Plant-A-Row Program in Chesapeake is part of a nationwide program initiated by the Garden Writers Association of America. On Tuesdays, June to September, you can share your garden bounty and canned goods with Chesapeake residents by dropping off at the Central Library, 9 a.m. to noon. Social distancing protocols are followed to ensure your safety. For more information, call Chesapeake Extension Office at 757-3826348.
Send questions to wkspen@gmail.com or to Home + Living c/o Daily Press, 703 Mariners Row, Newport News, VA 23606.