Tuesday, June 14, 2011

At Ease Disease, There's a Fungus Among Us

Powdery Mildew
We’ve had a wet spring and that
means two things—mosquitoes and diseases.  It doesn’t matter if it is cold and wet or warm and wet, some disease thrives in it.  Some plants are naturally more prone to fungal infections.  My monarda get powdery mildew every year and garden phlox are also susceptible.  Powdery mildew usually doesn’t do lasting harm, tho it can look a little unsightly.  Roses are also prone to many types of disease, including powdery mildew and black spot.  Other types of diseases can be devastating to some crops, including tomatoes, squash, and potatoes.
Mosaic disease
Plant diseases are spread in a variety of ways.  Sucking insects, like aphids, can transfer the disease and some diseases are spread by spores in the soil.  Rose Mosaic Virus is spread through vegetative propagation (cuttings).  Some are preventable, most are not treatable.

Late blight on tomatoes
The best way to fight disease is to follow good horticultural practices.  Water early in the morning and don’t water from overhead; that is water the soil not the plant.  In the vegetable garden, rotate your crops from year to year.  Mulch between the rows so soil borne spores aren’t splashed up onto the undersides of the lower leaves when it rains or when watering.  If you know you have plants that are susceptible to certain diseases, such as the monarda, or if your vegetables become diseased year after year, start applying fungicides before you see the problem and follow the good horticultural practices outlined above.  If you don’t catch it in time, the only thing to do is to remove the affected leaves or stems and begin a spaying program.  Dispose of the diseased material by putting it in a bag and then in the trash.  Do not throw the diseased prunings in the compost pile.  There are organic fungicides that you can use on vegetables and other edible crops, but always, always read and follow the label. 
You can also use seed or buy plants that are certified disease resistant.  When buying tomato plants, for example, you may see the letters VFNT, or only some of those letters.  The V stands for verticillium, the F for fusarium, the N for nematodes and the T for tobacco virus.  The Champion tomato variety is certified VFNT, which means it is genetically bred to be resistant to those for pathogens. 

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