Callisto injury to corn

Weed management faculty and staff at Iowa State University have received several calls concerning Callisto injury to corn. Many field visits have been made, and numerous samples have been assessed. Some of the situations involved insecticides applied previously to corn, some involved tank mix combinations with other herbicides (e.g., Steadfast), and some involved preemergence-applied herbicides (e.g., Balance) followed by a postemergence application of Callisto. In addition, numerous calls about injury from other herbicides have been received

Weed management in continuous corn

Despite the importance of glyphosate-based crop systems, there is a need for continued understanding about the management requirement for weed control in continuous corn production. The concern for timely weed management in order to protect corn yields becomes premier in postemergence (POST) herbicide corn systems, whether based on glyphosate or any other herbicide. Iowa State University recommends the use of herbicides that provide residual weed control in continuous corn regardless of the specific GM trait. The early preplant (EPP) or preemergence (PRE) application of residual herbicides is an excellent option to reduce weed management risks, improve environmental stewardship, and better utilize time at a critical period of the spring

Mesotrione carryover to soybeans

Mesotrione provides excellent residual control and breaks down readily in the soil provided there is sufficient moisture. Another important consideration is the rate of application, the timing of application, and soil characteristics likely influences the rate of degradation. Another possible consideration is the interaction of the atrazine included in Lumax with the mesotrione. Typically the mesotrione rate for a soil application of Callisto is approximately twice the rate when applied postemergence and is 0.24 and 0.1 lbs active ingredient/acre. The maximum rate of mesotrione in Lumax is 0.2 lbs active ingredient/acre

Make sure you know what you are spraying!

Given the difficulties in getting POST herbicides applied and the aggressive weed growth that is effectively reducing crop yields, it seems that due consideration of the details has been avoided. This has resulted in costly unintended consequences: loss of fields due to herbicide treatments contaminated with other herbicides or the application of the wrong herbicide (e.g., glyphosate applied to Liberty Link® corn). It is important that sprayers and nurse tanks be safely and thoroughly rinsed prior to switching herbicides and/or crops. Also, take the time to check and make sure you are spraying the correct field, corn hybrid, or soybean variety with the appropriate herbicide

Acetic acid (vinegar) for weed control revisited

An article in the June 3, 2002, Integrated Crop Management newsletter, page 91, described the use of acetic acid (vinegar) as a tool for controlling weeds. This article prompted a number of questions from growers and agribusiness personnel in Iowa. As a result of these questions, I contacted the USDA researchers that conducted the work and also checked a number of sites on the Web for information. The information below is from discussions with the researchers Dr. John Teasdale and Dr. Jay Radhakrishnan, and publicist Don Comis, and it is reported at several Web sites, including The Vinegar as an Herbicide Information Page andSpray Weeds with Vinegar

Weed Science Field Day 2002

The Weed Science Field Day will be held on June 27, 2002, at the Iowa State University Curtiss Farm on South State Street in Ames. The field day will begin with registration from 8:00 a.m. until 9:00 a.m. followed by a short program. Research and demonstrations of weed management techniques, herbicides, application strategies, and various crop traits will be available for review. Most of the ag chemical companies will be represented and available for discussions about their products. Farmers, ag chemical professionals, and the public are invited. Registration is $20, and refreshments and lunch will be provided. If you have questions, please contact me at (515) 294-1923 or e-mail [email protected]

2,4-D use in soybeans

Weed growth has increased considerably with the elevated soil temperatures and soil moisture availability. Thus, the use of a burndown treatment (see the May 4, 1998 ICM article, Burndown timing for no till fields, page 65) will be of critical importance for soybean production systems and 2,4-D is an excellent, cost-effective herbicide to use for broadleaf weed control. There are several factors to consider when determining which formulation and how much material to use

Waterhemp update

It was reported in the July 20 ICM newsletter (pages 146-147) that there were several incidents where weeds were not controlled by Roundup Ultra. Mention was made of a specific field near Everly, Iowa, where common waterhemp was surviving 3 applications of Roundup Ultra. This field was revisited and most of the common waterhemp plants have succumbed to the third application of 48 ounces of Roundup Ultra. The early applications included a 24-ounce treatment followed by a 36-ounce retreatment. Some plants that were collected from the site and transplanted in the greenhouse have survived all three applications, albeit with considerable damage. Our research efforts to elucidate the reason(s) for these control problems are underway

Pesticide drift in 1998

Recent weather conditions and poor decisions by commercial and private pesticide applicators have resulted in more drift complaints, to date, than normal. In discussions with Iowa State University Extension field specialists and Charles Eckermann (Pesticide Bureau, Iowa Department of Agriculture and Land Stewardship [IDALS]), it is apparent that pesticide drift complaints are widespread across Iowa. Eckermann reports that IDALS has received 34 drift complaints, the majority coming within the last nine days. Commercial pesticide application accounted for 30 of the complaints and four were attributed to private applicators