ISSUE 5 June 12, 2008
PREPARE FOR WEEDS AFTER PREEMERGENCE HERBICIDES
Successful preemergence herbicide programs require two key components. First, the programs need dry weather (with limited wind) in order to have the preemergence herbicides applied. Second, the programs generally need 0.5 to 1 inch of rainfall to activate the herbicide after the application, which moves the herbicide from the soil surface into the zone where weeds are germinating. Earlier this year, we struggled to get dry weather to get into fields to do tillage, plant, and apply herbicides. After that tough start of the season, it seemed inappropriate to hope for rain, but we need rain now to activate these herbicides. In eastern ND, after getting many of our trials planted and sprayed, we didn’t received the necessary rain for good herbicide performance. The same was true in other areas of the state.
As a consequence, weeds have emerged through preemergence herbicides treatments. The rain received since the latter part of May may activate some of these herbicides and reach back to control some of these weeds, depending on the species, their size, and the herbicide. However, the following actions may be very appropriate.
Action 1: Scout corn fields to determine how well preemergence herbicides were activated.
Action 2: Be prepared to apply a postemergence herbicide or cultivate if control is not satisfactory. Rotary hoeing would also be an option if done while the weeds are still emerging, but many growers may no longer have access to this technology.
RESOURCE FOR WEED CONTROL IN VEGETABLE CROPS
University of Wisconsin provides an on-line resource for pest control in most vegetable crops. See the following web site.
Wisconsin Vegetable Crop Update June 5, 2008, Issue #3 http://ipcm.wisc.edu/WCMNews/tabid/53/EntryID/548/Default.aspx
EXPRESS ON EXPRESS SUN SUNFLOWER
In the 2008 North Dakota Weed Control Guide page 35 it shows Express®, in both formulations - DF/WP and the new SG can be used for weed control in Express Sun sunflowers. Technically, the older DF or XP formulations, which are 75% ai, are not labeled for use on Express Sun tolerant sunflowers; only the newest Express® SG formulation is labeled, which is a 50% active material.
NEW 2008 HERBICIDE PRICES AVAILABLE
The new 2008 herbicide price list is now posted in the Weed Guide portion of the NDSU Weed Science - address is listed on the front and back of the weed guide.
Remember the prices are for small quantities and are averages of several retail sources. The prices also do not reflect any "program" offerings. Some prices will be higher and some lower than what you may get them for.
Most prices are the same or higher by a similar percent as other years. In general and as expected glyphosate prices are much higher than last year. Other herbicides prices increased more than expected, including atrazine, Basagran®, Callisto®, Pursuit®, and Raptor®. Prices of generic clethodim product varied widely.
Extension Weed Specialist