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Plant Pathology Infobytes

September 1, 1999

Tips for Disease-Free Turnip and Mustard Greens

Turnips and mustard greens grow great in the late summer and early fall garden. While getting a stand has been hard to achieve this season because of dry soils, devoted greens growers have generally been able to get their crops up and growing. With cooler temperatures and a little rainfall, turnips and mustard greens should take off and flourish.

Pest control is important in the late summer crop, since leaf feeders and other injurious insects often cause problems. Look in on the crop every few days , and if problems are spotted, they can generally be handled with application of a recommended insecticide. If you aren't sure about the type of material to apply, check with your county Extension office for suggestions.

While you're checking your crop, keep a sharp lookout for early symptoms of fungus diseases which sometimes move in and blight a mustard or turnip planting. The most common fungus disease that affects leafy greens is white spot. Symptoms of this disease include circular, gray to brown or almost paper white spots. As the spots increase in size and number, the entire leaf may become blighted and is no longer suitable for harvesting.

The fungi responsible for white spot and some of the other diseases that affect leafy greens are carried over in the soil for a period of several years. Also, you're more likely to have blight problems if you planted your crop with seed saved from a planting where white spot was a previous problem . So, it's best to start a new planting of turnips or mustard with new seeds (preferably those treated with a fungicide). Hopefully, these seed were planted in an area of your garden where greens haven't been produced within the past two years.

Rotation and new seed pay off, but these practices alone won't stop an attack of fungus disease on your greens, so use them in combination with other disease control measures to keep leafy green blight under control and improve crop quality.

If you aren't currently spraying your greens with a fungicide, consider giving the following control measures a try. Fungicides will protect greens from infection, provided spray applications are made early in the season. Don't wait until disease symptoms are widespread on your greens before applying a fungicide.

Initiate a fungicide application program and spray on a regular basis. For best results, begin early and continued throughout the season. Approved fungicides include those containing copper as the active ingredient. Kocide DF, a copper based fungicide, available in one to two pound containers at many farm and garden supply dealers, may be applied to turnips and mustard, as well as collard greens every 7 to 10 days. Dilute at the rate of 1/2 to 1 tablespoonful per gallon of water. Other formulations of Kocide may be available, as well as other copper-containing fungicides, so check with your dealer for product availability.

An added advantage of these fungicides is the fact they may be mixed with a recommended insecticide, thus allowing a "one-shot" application for disease as well as insect control. Note: Read label directions for harvest restrictions. While there is a "zero" day waiting period for most copper fungicides, this may not be true for the insecticide. If you have questions about pest control in your fall garden, check with your county Extension office.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.