JANUARY
2007

 

 

 

By
B. Rosie Lerner
 
Purdue
Extension
Consumer Horticulturist

 

 

 

 

 

01-04-07

Question and Answer

Q. Concerning the question about deer and other wild animals eating plants, bushes, and young tree growth, etc.: We were told (and experienced) to tie (a particular brand of deodorant) soap to all trees and bushes to keep deer from eating our landscaping. It works for us. We have seen as many as 40 head in our area in Steuben County. They are here! And before, we tried everything.

A. Your soapy landscape plants are in good company! There have been some studies and numerous testimonials from landowners indicating that any ordinary bar of soap can provide some protection to landscape plants. You can drill a hole in the bar of soap and suspend it from a branch with twine or even a twist tie. The studies indicate that one bar protects up to a radius of 3 feet, so you may need to hang several bars on larger plants. For more information on protecting your landscape from deer damage, visit the Purdue/USDA Wildlife Conflicts Information Hotline online at http://www.entm.purdue.edu/wildlife/wild.htm.

Q. Last summer our tomato plants started dying from the bottom up and were dead long before the growing season was over. Any help for next year would be appreciated. Also, I purchased many unusual gourds from a local vegetable stand. How is the best way to dry them or dry them to save the seeds for next year?

A. While tomatoes are plagued by a stunning array of disease and insect problems, the symptoms you describe are most likely caused by one of these three common fungal diseases: Septoria leaf spot, early blight or late blight. Because these fungal diseases spread by spores, which require a layer of moisture on the foliage to infect the plant, they are most severe during wet weather.

Septoria leaf spot, sometimes called Septoria blight, usually appears on the lower leaves after the first fruits set. Fruits are rarely infected directly, but the loss of good foliage reduces fruit yield and quality, and exposed fruits are more susceptible to sunscald. The fungus is spread by splashing water and by working among the plants when they are wet. It overwinters on tomato and weed debris.

Early blight also appears on the lower leaves, usually after a heavy fruit set. The spots are dark brown to black and form concentric rings that form what is often called a bull’s eye. The tissue around each target spot turns yellow, and soon the entire leaf turns yellow and drops. Early blight fungus also infects stems and may produce stem cankers. It occasionally attacks the fruit, producing large sunken black target spots on the stem end of the fruit. Infected fruits often drop before they mature. This disease is most common late in the growing season. The fungus overwinters on old tomato vines and on weeds in the nightshade family.

Late blight occurs in moist weather with cool nights and moderately warm days. Dark, wet-looking spots begin spreading in from the leaf edge and may develop a downy white growth on the lower leaf surface during wet weather. Fruits may also develop spots that are gray-green and water-soaked at first, but they soon enlarge and turn dark brown and firm, with a rough surface. When conditions are favorable, the disease may progress very rapidly.

There are a number of management practices that can help reduce the occurrence of these diseases. Crop rotation would help, but, in a small garden, this would mean only planting tomatoes once in three or four years. Most gardeners won’t be willing to forgo their beloved tomatoes that long!

Good garden sanitation can help reduce the carryover of disease from year to year. Remove badly diseased leaves as soon as the spots are detected and rouge out badly infected plants ASAP. Remove and destroy all tomato plants after killing frost.

Keep the foliage of the plants as dry as possible. Allow plenty of space between plants for good air circulation. Avoid watering with overhead sprinklers in late afternoon or evening. Plants that stay wet all night provide the perfect conditions for fungal spores to infect. Use trickle or drip irrigation where feasible.

Fungicides can help protect healthy foliage from becoming infected, but they cannot cure an infection once it is present. These diseases can spread rapidly and, once established, are difficult to control. Apply early in the season, and re-apply following a rain and repeat throughout the growing season per label directions. Be sure to read label directions thoroughly BEFORE you apply and be mindful of the harvest interval restrictions. For example, chlorothalonil fungicide can be applied up to the day of harvest, but mancozeb must be applied no later than five days prior to fruit harvest.

Q. We have several Hostas in our landscaping. During the heat of summer, they look terrible, although in spring and late fall they are OK. Could you give me the names of some Hostas that withstand the heat better?

A. Well, this could be a loaded question, but I’ll bite! With literally hundreds of species and thousands of cultivars, you will likely have as many different opinions as to which ones might be more heat tolerant. But it’s difficult to discuss tolerance of just temperature extremes without considering other environmental factors.

In general, most hostas prefer moderate shade or at least high-filtered shade from trees and well-drained, loose soil. But individual cultivars will vary in their ability to tolerate extremes. Heat tolerance can be improved if provided adequate shade and/or plenty of water. The blue cultivars tend to look greener in the sun and heat, because their blueness is actually a waxy layer on the outside of the leaf that “melts away” in the heat. The yellow-gold cultivars seem to tolerate sun best, but not uniformly so.

For more information on hosta, visit the American Hosta Society, http://www.hosta.org, and the Indianapolis Hosta Society, http://www.indianapolishostasociety.org. And for serious Hosta fans, the National Hosta Society convention will be hosted in Indianapolis, June 20-23, 2007. For more information on this event, see http://www.hosta2007.org.

 

Writer: B. Rosie Lerner
Editor: Olivia Maddox,