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????

Winter Temperatures, Corn Flea Beetle Survival, and Potential for Stewart’s Wilt

• Corn flea beetle winter survival is expected to be low in northern and central Indiana.
• Moderate survival is expected for southern Indiana, higher in the Ohio River valley.
• Corn flea beetle is a vector of Stewart’s bacterial wilt and leaf blight of corn.
• Seed applied insecticides generally prevent early corn flea beetle feeding.

 

Corn flea beetle is a sporadic corn pest in Indiana and has had little impact of recent years. Still, winter temperatures in regions where beetles were abundant last season will determine if there is cause to be concerned this spring for susceptible inbreds and hybrids. This is especially important since this insect transmits the bacterium that causes Stewart’s disease in corn. The severity of the disease correlates with last season’s beetle abundance and this winter’s temperatures. This is because the Stewart’s wilt bacterium survives in the gut of the overwintering beetles and depends upon the beetle to infect corn. Warmer temperatures result in higher beetle survival, and therefore a greater potential for Stewart’s disease. <Read More> 

 

Workshop Helps Entrepreneurs Cook Up a Home Food Business

Midwestern entrepreneurs interested in starting their own food business can learn how to begin and grow their enterprise at a Purdue Extension workshop in Indianapolis.

"An Introduction to Starting a Specialty Food Business in Indiana" will be held April 25 from 7:45 a.m. to 5 p.m. at the Indiana Farm Bureau offices, 225 S. East St. Sessions will cover a variety of topics, including business planning, marketing, entrepreneurship, product development and packaging, as well as issues specific to food businesses, such as food safety, food regulations and organic products.

 

Featured presenters will include Sharon Farrell of the Indiana State Department of Health and Cissy Bowman and Jessica Ervin of Indiana Certified Organic.

 

Other presenters will be Purdue's Katherine Clayton, food science Extension outreach specialist; Maria Marshall, agricultural economics associate professor; and Steve Smith, managing director of the Food Science Pilot Plant and Sensory Laboratories.

 

"This workshop is a great introduction to all of the issues that you're going to have to deal with before you start a food business," Marshall said. "The food industry is very competitive, and this workshop will help you make sure you know what you're getting into."

 

Registration is $100 per person and is due by April 17. For more information or to register, click here or contact Marsha Pritchard at 765-494-0889 or mpritcha@purdue.edu.