Ron Kujawski: Wet July could bring plant disease


According to the keepers of the Doppler (a.k.a. National Weather Service), this past July was the second wettest July on record for Berkshire County. What does this mean for gardeners?

For one, it means that not much time was spent sipping mint juleps under the old oak tree, the one with the yellow ribbon tied around it. It also means that we can expect plant diseases to become more apparent during August, a normally hot and humid month. Most plant diseases not only thrive in moist environments, but are also dispersed as rain splashes spores of disease-causing fungi from one part of a plant to another and from one plant to another. With heat and humidity, disease infections will develop quickly. Well, I can't stop the rain, but I can suggest a few things to possibly slow development of diseases.

Most likely, disease infections have already occurred and, therefore, applying fungicides now will not cure any existing diseases. However, fungicides may stop, or at least slow, their spread. Pruning diseased plant parts is another option. This will help eliminate potential sources of fungal spores. Do this only when the plants are dry. Except for vascular diseases, such as fire blight or oozing cankers, it is not necessary to disinfect pruning tools between cuts. Finally, thinning plants by judicial pruning will improve air circulation around plants and reduce incidence of diseases such as leaf spots and powdery mildew.

Another consequence of the second rainiest July on record is the leaching of plant nutrients from the soil. The nutrients most likely to have been leached are nitrogen and potassium. Loss of nitrogen in particular causes foliage of many plants, especially annual flowers and vegetable crops, to fade to pale green or yellow. Correcting these nutrient deficiencies is much easier than dealing with diseases. Simply apply high nitrogen fertilizer to affected plants. The quickest response can be had by using water soluble fertilizers. It won't be necessary to apply fertilizer to onions and other crops, which are at the end of their growth cycle.


"If raindrops keep falling on my head," I can still:

n Preserve the surplus from the vegetable garden by canning, freezing or dehydrating the vegetables. If you have no experience in canning or freezing garden vegetables, seek out a friend who has such experience, or attend a class on food preservation. Two of the best reference books on food preservation are: "The Ball Blue Book of Preserving" and "Keeping the Harvest" by Nancy Chioffi and Gretchen Mead (Storey Publishing).

n Sow seed of sweet William, foxglove, Canterbury bells, hollyhock, black-eyed Susan, viola and pansies directly into the flower garden, in a seed bed or in flower pots. All of these flowers are biennials, that is, they have a two-year growing cycle. The plants will grow stems and leaves the rest of this year, produce flowers next year, and then die.

n Prune out the old canes from raspberry plants and thin the new canes, leaving three or four canes per linear foot of row.

n Buy and plant container-grown perennials, trees and shrubs. Soils moisture levels are ideal for new plantings. Just the same, place a layer -- no more than three inches deep -- of mulch around, but not in contact with, the plants. When buying container-grown plants, avoid those that are wilted, have browned foliage and are not pot bound. Don't be afraid to remove a plant from its container -- with the help of a garden center employee if necessary -- and inspect the roots.

n Have soils tested for pH by Western Massachusetts Master Gardeners at the Berkshire Mall Farmers Market on Saturday, Aug. 23 from 9 a.m. to noon. Directions for obtaining soil for testing may be found on the web site. There is a suggested donation of $1 for soil testing.


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