PLANTING SOYBEAN IN JUNE?
The recommended planting dates for soybean are May 10 to 25. Delays in planting may likely result in reduced seed yield and quality. If soybean are planted after May, earlier-maturing varieties should be used compared to your variety choice if planted during the recommended period.
How much will seed yield be reduced if soybean are planted in early June? In a two-year soybean study at the NDSU Carrington Research Extension Center, effects of planting dates and varieties were measured. Traill (0.0 maturity group) and Daksoy (00.5 maturity group) were planted in mid May and the first week of June. Averaged across years (1999-2000) and varieties, seed yield was reduced about 2.4 bushels/acre or 6% with late planting. The yield loss with late-planted Traill averaged 2.8 bushels/acre or 7% compared to planting on May 18 or 20. However, planting dates did not affect the yield of Daksoy, the early-maturing variety.
EARLY-SEASON TAN SPOT CONTROL IN WHEAT
Our recent pattern of frequent rains is likely to provide the environment for tan spot development in wheat. Fungicides may be used to suppress early-season tan spot. Consider a fungicide application if the following conditions exist: 1) wheat was planted in wheat stubble; 2) tan spot infections are evident on young leaves; 3) good wheat yield potential exists; and 4) short-term weather forecasts appear favorable for disease development. Fungicides (and rates) labeled for early-season application in wheat include: Tilt (2 fl oz/A), mancozeb (1 lb/A), and Stratego (5 fl oz/A).
NDSU wheat fungicide trials have included early-season fungicide treatments. In 1992, an average of five % yield increase to mancozeb was measured over four locations compared to untreated checks, while a seven % yield increase occurred with fungicides across seven sites in 1993. In 1994, variable responses to early-season fungicides occurred, with several sites showing no yield increase while other sites responded with 10 to 15 % yield increases. At the NDSU Carrington Research Extension Center, 4-year average (1994-96, 1999) yield with Tilt at 2 fl oz/A applied to 5- to 5.5-leaf wheat was similar (35.3 bushels/A) to the untreated check (35.1 bushels/A).
Fungicides are often tank-mixed with herbicides for application to 3- to 5-leaf wheat. If planning to tankmix a fungicide with herbicides, refer to pesticide labels and the NDSU Extension Service circular W-253 “2001 ND Weed Control Guide” for recommendations.