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Fire Blight, Insects, and Blossom End Rot of Tomatoes
By John Fulton

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[June 24, 2016]  Fire Blight - Apple and pear trees continue to have their problems. There is a large amount of tip dieback in some varieties, and this is probably fire blight. Tip dieback has become very evident the past couple of weeks, and even where the spray programs were followed in home orchards.

This would actually be the second bout for the year. Look for a shepherd’s crook at the tip of the affected areas as a clue it is fire blight. Fire blight is a bacterial disease, therefore there is little chance for you to treat it. The common treatment in commercial operations is streptomycin, but it has to be applied before symptoms appear. Copper or Bordeaux mixture can also help prevent, and that means prevent and not cure, the disease in some years. Prune out disease cankers when dormant. The ornamental pears are moderately resistant, but dead tips are common again this year. These also provide a source of the disease for other susceptible hosts.


Insects



One insect of note with the wet weather earlier this year is the earwig. Earwigs tend to be in high organic areas, as they feed primarily on dead insects and plant material. However, they can, and do, eat live plant material such as marigolds, zinnias, strawberries, and others. They may be a prime suspect if you notice damage, but never see any insects during the day. Control can be obtained with insecticides such as bifenthrin or permethrin.

The inconspicuous potato leafhopper has been a problem for the past week as well. This is the small wedge-shaped, light green insect that seems to just fog around security and patio lights. They are also small enough to come in through screens after dark. They are not only a nuisance, but they can cause damage to a wide variety of plants.

Potatoes are the first plant that comes to mind when we talk about potato leafhoppers (must be something about the name), but many other plants ranging from beans to trees can be affected. You may be wondering what kind of damage a few little leafhoppers can do, especially since they suck sap from plants and aren't that big in size.

Leafhoppers suck sap and then inject a toxin back into the plant. Along the same lines as humans getting a mosquito bite - it's the extra that's injected back in that causes the injury. Symptoms of leafhopper damage start as yellow "v" shaped areas on the tips of leaves. These areas turn brown or black and then fall out leaving a "v" shaped hole on the tip of the leaf. This is a symptom, but not the only injury. Large numbers of leafhoppers can kill potato and other plants.

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Controls for leafhoppers are warranted with very low numbers. In alfalfa fields, it is recommended to treat when 2 leafhoppers are caught in a sweep net in alfalfa over a foot tall. Garden treatment options for potatoes include Sevin, bifenthrin, permethrin, and rotenone as common insecticide choices available to homeowners. Most trees and shrubs can be treated with Sevin, permethrin, or bifenthrin.

Blossom End Rot of Tomatoes



Blossom end rot is a non-infectious disease (caused by the weather and growing conditions) which is very common during extended dry periods. It also seems to be worse on tomatoes grown in containers. The alternating weather patterns we have experienced have set us up for problems.

It begins as light tan water-soaked lesion on the blossom end of the fruit. The lesions enlarge and turn black and leathery. This can drastically lower the yield and lower marketability of the fruits. Fluctuating soil moisture supply during the dry periods, and low calcium levels in the fruit are the major causal factors. Control of blossom end rot consists of providing adequate moisture from fruit formation to maturity, and use of mulch (grass clippings, plastic, straw, shredded newspapers, or plastic) to conserve moisture and even out the moisture supply. If you don’t have a mulch in place now, it is best to apply soon to prevent problems. Also, avoid frequent shallow watering. Water deep and then wait five or more days before watering again. This is one reason this problem is very common in container grown tomatoes.
 

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]

 

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