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ISSUE 7  June 18, 1998

 

THESE CROPS THRIVE WHEN BEES ABOUND

    Some years the fruit trees and vegetable crops produce more than we can consume; other years, the production is poor, or the fruit poorly shaped. Bees are major role players in the development and quality of the fruits and vegetables that grow in our gardens, yards, and orchards. Here are the crops that are most influenced by bee activity:

    *Cucumber, squash, pumpkins and watermelon have both male and female flowers, and require insects to carry the heavy pollen from male to female flowers. Research has shown that bumble-bees are more efficient than honeybees at pollinating. Fruit set is best when there are plenty of bees in the field, and each flower is visited many times.

    *Cantaloupe plants have both perfect flowers (male and female reproductive structures in the same flower) and imperfect male flowers. The perfect flowers cannot self-pollinate, so bees are needed to move the heavy pollen. The stigma is receptive to pollen for only a few hours, and when the weather is hot, for only a few minutes. Bee visitation to these flowers in the early morning is crucial to good fruit set.

    *Strawberries (now available locally!) are pollinated by both wind and insects, but fruit shape is best when flowers are visited by a diversity of bee species. The strawberry flower is multi-pistiled, and must be evenly pollinated to make the nicely shaped fruit we all look for!

    *Tomatoes are pollinated when a flower is shaken, either by wind or insects. Bumble-bees make good pollinators because their buzzing shakes the flower.

    *Apples, pears, and June berries all set better fruit if visited by many bees.

    Keep in mind that bee activity can be greatly curbed if the weather is poor (rainy, cold, windy) at the time the pollen is mature. Bad weather at that critical time could result in greatly reduced fruit set. Also, spraying insecticides at the times of bee activity will certainly have a negative affect on the bee population, and result in poor fruit set.

Ron Smith
NDSU Extension Horticulturist
and Turfgrass Specialist

 

PESTICIDE CONTAMINATED SPRAY TANKS AND CROP INJURY

    This past year in Iowa, a major liability insurer of commercial pesticide application firms dished out over $1.3 million in damage claims for misapplication of pesticides-specifically from contaminated spray tanks. The problem occurs when the applicator fails to adequately clean out or neutralize a herbicide in a spray system before he uses the equipment on a susceptible crop.

    This problem has become more of an issue in recent years because we are raising more and more crops with varying degrees of cross susceptibility to herbicides. In North Dakota we produce dozens of different crops. In Iowa we are talking only a few, principally corn and soybeans. In addition, the herbicides we utilize today are biologically active at rates as low as parts per billion and neutralizing agents are becoming chemical specific. Using only ammonia is no longer adequate for many pesticide. In the next several weeks producers in North Dakota will be shifting their applications from herbicides, to either fungicides, or insecticides. Proper neutralization of herbicides will be key to avoiding huge financial losses. What follows are some tips taken from the 1998 ND Weed Control Guide.

    Step 1: Drain tank and thoroughly rinse interior surfaces of tank with clean water. Spray rinse water through the spray broom. Sufficient rinse water should be used for five minutes or more of spraying through the boom.

    Step 2: Fill the spray tank with clean water and add a cleaning solution (many labels provide recommended cleaning solutions). Fill the boom, hoses, and nozzles and allow the agitator to operate for 15 minutes.

    Step 3: Allow the sprayer to sit for at least eight hours while full of cleaning solution. The cleaning solution should stay in the sprayer for at least eight hours so that the herbicide can be fully desorbed from the residues in the sprayer.

    Step 4: Spray the cleaning solution through the booms.

    Step 5: Clean nozzles, screens, and filter. Rinse the sprayer to remove cleaning solution and spray rinsate through the booms.

    More information on this issue may be found on page 62 of the 1998 ND Weed Control Guide. Also, consult the label for more specific directions for sprayer cleanup.

Andrew A. Thostenson
NDSU Pesticide Program Specialist


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