Agricultural news

How rainfall effects preemergence herbicides Bob Hartzler, weed scientist at Iowa State, wrote an interesting article on how rainfall affects preemergence herbicides. Pre-emergence herbicides are those that are applied after planting but before the crop emerges. The effectiveness of herbicides applied at this time is greatly influenced by rainfall. Herbicides need to be present for most weed species at germination in the upper two inches of soil. Rainfall helps incorporate herbicides such as Dual, Frontier and Harness to the two-inch depth. Research in Illinois found the control of foxtail with preemergence products to be approximately 50 percent without rainfall. Control increased to the 70 – 75 percent level with 0.25 inches of rainfall, 90 percent with .5 inches, and control was 100 percent with 1.0 inch of rainfall. Dual needed a bit more rainfall than either Frontier or Harness for comparable weed control. Rainfall has been above normal this spring, so I would anticipate weed control to be excellent for growers using preemergence herbicides. I have seen nearly perfect stands too, so our corn crop should be off to a great start. Soybean planting has been delayed due to wet weather. As of May 21, we had less than 50 percent of our soybean acreage in Meeker County planted. Concerns of planting full season soybeans Rainy weather has delayed soybean planting in much of Minnesota. Some counties have nearly all their soybeans planted while others have just gotten started. The question comes up at this time of year as to when to switch to a shorter season soybean variety. Our research data shows growers should move to shorter season varieties around June 10. Up until June 10, growers have the best yield potential with full-season varieties. Around June 10, we would recommend growers switch to a variety with a relative maturity rating of 0.5 units shorter than the original soybeans. Soybeans are driven by photoperiod and catch up somewhat if planted later in the growing season. The same variety planted May 1 and May 30 may mature only 10 days apart. Seed companies have developed many good maturity soybean varieties for the northern portion of Minnesota and North Dakota that have excellent yield potential. Asgrow 0801 is one of the more popular soybean varieties in the United States. Growers who planted it two years ago following the windstorm through this area in mid- June harvested more than 40 bushels per acre. Horticulture notes Poison ivy is up and growing now. To identify poison ivy, watch for three shiny leaves that have pointed tips. Leaves vary quite a bit in size depending on soil fertility and sunlight. Later in the season, plants produce clusters of white fruit in the axils of leaves. Another clue for identification is leaves emerge intermittently on an underground stem, somewhat like creeping Charlie. Roundup is the best herbicide for controlling poison ivy and needs to be applied at the full rate. Planting vegetable garden seeds in a mound will speed up germination and growth. Ridge till farmers plant their corn and soybeans in the ridge for this same reason. If garden space is limited, use some type of fence or trellis so plants grow up rather than out. Peas, cucumbers and pole beans can all be planted near a fence line to save space in the garden. Remember to water gardens and lawns in the morning hours and avoid late afternoons and evenings. We are setting up ideal conditions for diseases when we water late in the day.