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Soybean population, continued...By David G. Hallauer Meadowlark District Extension agent, crops, soils, horticulture A recent column discussed research suggesting a final stand of 100,000 soybean plants per acre would be sufficient in most cases to maximize yield. Easier said than done. If producers aim for a population of about 100,000, what seeding rate should they use? At 80 percent emergence, you'll need about 130,000 seeds per acre or a little more. In 30-inch rows, that's 7.5 seeds per foot. In 7.5-inch rows, 1.875 seeds per foot. Remember, however, that emergence can be highly variable (in the 26 tests discussed last week, emergence ranged from less than 50 percent to near 100 percent). Another interesting finding was the observation of emergence at different seeding rates. At seeding rates less than 150,000 seeds per acre, field emergence averaged close to 80 percent. When more than 150,000 seeds per acre were planted, emergence was actually reduced to an average of 75 percent. This seems to run counter to the conventional wisdom of the use of higher seeding rates to get better germination--one emerging seed helping adjacent seeds push up through the soil. The emergence rate on soybeans depends on equipment limitations as well as soil and weather conditions at and soon after planting. Be sure to plant enough seeds to result in the desired population, given your expectations regarding field emergence. Pine tip blight control Pine tip blight last year was as bad as I've ever seen, predominantly due to our stressing Easter freeze. Getting a step ahead of the disease this year is key, and that means treating infected pines as new buds are elongating, usually the third week of April Austrian, mugo, Ponderosa and Scots pines are all susceptible to tip blight, which survives in dead shoots, branches, or pine cones. Labeled fungicides for controlling the disease include copper compounds (e.g., Bordeaux Mixture) and fungicides that contain thiophanate-methyl (Fungo, Cleary's 3336). Remove Dead Pines NOW. If you have trees infected by pine wilt, remove them now. Pine wilt continues to spread via transmission of the pinewood nematode from these dead trees. Infected trees need to be cut to the ground--no stump--and chipped, burned or buried ASAP (by April 15 if possible.) Pine wilt symptoms appear between August and December with affected trees wilting and dying within a few weeks to several months. The needles turn gray, then yellow and finally brown. This may occur branch by branch or all at one. The needles stay attached for up to a year. More information is available online at www.oznet.ksu.edu/library/plant2/MF2425.pdf. Use mild, soluble fertilizer for early transplants To avoid phosphorous deficiencies with newly planted flower/vegetable transplants in to our cool spring soils, plan to use a mild fertilizer solution to kick them off right. The base for a homemade transplant solution is a fertilizer that contains more phosphorus than nitrogen or potassium. Examples of that kind of N-P-K combination include 5-10-5, 10-20-10 and 11-15-11. Put 2 to 3 tablespoons of the fertilizer in a gallon of water several hours before use. Then apply about 1 cup of solution per transplant. 4/21/08 Date: 4/15/08
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