Friday, April 19, 2013

Spring Burndown Applications To Weeds And Cover Crops

This spring so far has been cold and wet with short spurts of warm sunny days in-between. This weather cycle for the most part kept producers out of field and allowed the winter annual weeds to flourish the past couple of weeks. As we look ahead to the next couple of weeks in hope of getting out to the fields to do spring no-till burndown applications, there are a couple of things to keep in mind. <Read More>

The Planting Date Conundrum for Corn

Conventional wisdom says that the prime planting window to maximize corn yields in much of Indiana opens about April 20 and closes about May 10. This “window” typically opens about one week later across the northern tier of Indiana counties (later warmup) and about one week earlier across the southern tier of Indiana counties (earlier warmup).

Very little corn, if any, has been planted in Indiana yet this spring as of 14 April. By itself, this is not much cause for concern because typically only a very small percentage of acres are ever planted by this date in Indiana. However, the specter of delayed planting is clearly on the horizon because little other spring fieldwork has been completed due to the frequent and sometimes excessive rainfall in recent weeks. For some growers, tillage operations, herbicide applications, and nitrogen fertilizer applications must be completed first before they can consider planting their crops.

What are the consequences of a delayed start to planting? How important a predictor of statewide corn yield is planting date anyway? Does late planting in and of itself guarantee lower than normal yields? Good questions, but the effect of planting date on statewide average corn yield is not clearcut. <Read More>

Tuesday, March 26, 2013

Impact of Cool Temperatures on Wheat Herbicides

Jim Martin, University of Kentucky Extension Weed Scientist

Snow covered wheat in late March

The cool temperatures we experienced this spring caused some wheat growers to delay herbicide applications in anticipation of better weather. Stress conditions such as cool temps tend to limit physiological process in plants; therefore, slowing the response of weeds to the herbicide. The desired level of control may eventually be achieved; however, in some instances the slower activity may allow time for some weeds to recover. The slower activity caused by environmental stress, such as cool temperatures, may also limit wheat’s ability to metabolize herbicides, thus resulting in injury. 

The immediate forecast doesn’t look favorable which prompts growers to ask “Do I spray or wait for better weather?”  

The logical choice would be to wait for improved conditions if the size and number of weeds are small. However, if the size or number of weeds dictates to spray, consider an herbicide option that has the greatest margin of safety and is effective on the weeds that are present. Cool temperatures may have less of an impact on controlling weeds that are highly susceptible than those that are marginally susceptible.  

The following are some tips to consider as we progress through the next few days,

• Harmony and Harmony Extra are examples of ALS- inhibitor herbicides that can injure wheat in cool wet soil conditions. Injury may also occur if wide fluctuations of day and nighttime temperatures occur prior to, or soon after, application It is not clear to what extent, if any, the injury observed for Harmony and Harmony Extra impacts wheat yield. The labels of these products recommend adding 2,4-D as a tank mix partner to limit the risk of injuring wheat from the ALS-inhibitor herbicides. It is important to recognize the safest time to use 2,4-D in wheat is when plants are fully tillered and prior to jointing. 

• Some growers may be tempted to include Clarity, Banvel, or other products that contain dicamba as a tankmix partner with other herbicides to enhance control of certain broadleaf weeds. Avoid using dicamba once wheat begins to joint in order to limit the risk of injuring wheat.

• When controlling wild garlic with Harmony, Harmony Extra, or similar generic products, allow time for plants to develop 2 to 4 inches of actively growing tissue. The new growth emerges from the base of the plants and not from the old leaves that have tip burn from cold temperatures.

Is it Spring Yet????