Posted 14 July 2009. PMN Crop News.
Don’t Forget Silage Corn When Scouting
Source: Dow AgroSciences Press Release. www.dowagro.com
Indianapolis, Indiana (June 15, 2009)--Taking time this summer to scout cornfields can mean the difference between a successful harvest or losing yield to diseases and insects. While it is important to scout fields being harvested for grain, early season scouting can return even greater benefits in silage corn.
“Diseases and insects affect yield and standability, but also have a major impact on forage quality,” says Mark Riehl, customer agronomist at Mycogen Seeds.
“When growing grain corn, we want the plant to take full advantage of its leaf area in order to optimize ear growth and kernel development. With corn silage, we need grain fill but we also want to protect the integrity of the leaves and stalks throughout the season,” he says.
Riehl points out that leaves in good condition are more easily digested and increase tonnage at harvest. Therefore it is critical to keep all leaves as disease- and insect-free as possible, not just the ones affecting grain fill. Early scouting can help catch problems before plant damage becomes significant.
Diseases that cause the most economic damage to silage include gray leaf spot, northern and southern corn leaf blight, eye spot and corn leaf rust. It’s important to learn the distinguishing characteristics of these particular plant maladies for accurate identification and treatment, Riehl says.
“Several universities offer disease identification guides, as well as newsletter updates on diseases and insects that have been spotted in your area. If you are not on a mailing list for these reports, it would be a good idea to subscribe to a local newsletter and keep alert for potential threats.”
Riehl recommends that silage growers start scouting for diseases near the end of June or the beginning of July. Timing can vary depending on geography and the stage of plant development, but the key is to get into the field approximately 10 days before tasseling begins.
“If a problem is spotted, it is important to take action as soon as possible,” Riehl says. “Because most fungicides are preventive, the earlier you can apply the treatment, the better the control will be. Under the right weather conditions, even a few diseased specks on the leaves can become a serious issue if not treated.”
The two classes of fungicides used to treat the most common diseases in corn are triazole and strobilurins. Triazole products such as PropiMax® EC fungicide can be used before and through tasseling, while strobilurins or combinations of strobilurins and triazole should be used after a majority of the corn has tasseled. The effectiveness of both classes of fungicides is relatively similar and either one does a good job of preventing diseases.
Mycogen Seeds offers several silage hybrids that have been bred for tolerance to diseases, especially gray leaf spot. MYCOGEN® brand SILAGE-SPECIFIC™ TMF silage hybrids have excellent disease tolerance. MYCOGEN brand SILAGE-SPECIFIC BMR hybrids also offer some tolerance, but it is still important to monitor fields and use a fungicide treatment if thresholds are reached. In addition, both TMF and BMR hybrids are available with HERCULEX® I Insect Protection or HERCULEX XTRA Insect Protection, which provide excellent above-ground insect control.
If a fungicide treatment becomes necessary, keep in mind that micronutrients and/or insect control products can be added to those applications. Consult your Mycogen Seeds customer agronomist for specific hybrid information on disease control as well as micronutrient combination recommendations.