Wireworm Fields Wanted

With early season insect concerns becoming more common, we are looking for fields that have a history of wireworm problems to put out some insecticide screening trials. Preferably, these fields have a population confirmed this spring by the use of wireworm traps. Please contact Keith at 402-370-4016 or email him at kjarvi1@unl.edu if you are interested in helping us out. Thanks!
(KJ)

Alfalfa Update

We should start seeing problems in alfalfa greenup by now if there are any army cutworms out. Invest some time in the next few days and make sure your alfalfa is getting off to a good start. It is still a little early for alfalfa weevil feeding but in the next 7 to 10 days we should be getting enough heat units to begin seeing some damage. More on alfalfa weevils in the next newsletter.
(KJ)

More on control of winter annual weed species

Winter annuals are species that germinate in the fall, overwinter and then continue growing in early spring. Drier fall weather usually reduces the number of winter annuals due to lower germination rates because of lack of moisture. Long and cold winters with the snow cover less than 3 inches deep can also reduce their survival rate. However, more than 3 inches of snow cover can increase their survival rates. The rapid growth of winter annuals starts as soon as the soil temperatures reach around 50-55 F. The list of the most commonly known winter annuals include: field pennycress, shepherds purse, henbit, blue mustard and treacle mustard (bushy wallflower). You may want to watch for those species. They make the Agreen patches@ that are commonly seen during late parts of the year (October, November) and early spring (March-April). In addition, dandelion and curly dock, which are not winter annuals, can be also seen in early spring and the time of corn and soybean planting.

These weeds can be controlled both by mechanical means and herbicides. If you are in a conventional tillage situation, the herbicide application may not be necessary. In most cases soil preparation prior to planting will disturb and provide adequate control of winter annuals.

In no-till fields, winter annuals can be effectively controlled with various herbicides. In corn and soybean they can be controlled 0-45 days before crop planting depending on the herbicide or after crop planting but before crop emergence. The same is true for the fields that are planted with the herbicide tolerant crops (e.g. Roundup-Ready or Liberty-Link crops). The use of pre-plant or pre-emergence herbicides with residual activity in Roundup Ready crops would also provide a longer comfort zone in which to apply Roundup. Winter annuals are usually controlled in the first two weeks of May, before they become too large for herbicide efficacy.

Examples of burndown herbicides that can be used in corn and grain sorghum include: Aim (0.3 oz/acre), 2-4-D Ester (1.0 pt/acre); 2,4-D Ester + Banvel (0.5 pt + 0.5 pt); Banvel (Atrazine (2 qt); Atrazine + Banvel (2 qt + 0.5 pt), Atrazine + 2,4-D (2.0 qt + 1.0 pt); Field Master (4 qts), Gramoxone Extra (1.5 pt); Gramoxone extra + Atrazine (1.5 pt + 2.0 qt); Roundup Ultra Max (18-26 oz), Touchdown (24-32 oz/acre) and one of many generic Glyphosate type products (24-32 oz). The list of pre-emergence herbicides in corn includes: Atrazine, Axiom, Balance, Bladex, and Prowl.

Examples of burndown herbicides in soybean that can be used from 0-30 days before crop planting include: Aim (0.3 oz/acre), Canopy (5-7 oz/acre), Command 3E (1.5 pt/acre); Gramoxone Extra (1.5 pt/acre); Extreme (3 pts/acre), Gauntlet (co-pack, 5.33 + 0.6 oz), Pursuit (4 oz), Pursuit Plus (2.5 pt), Sencor/Lexone DF (16/13 oz), Roundup Ultra Max (18-26 oz), Touchdown (24-32 oz/acre) and one of many generic Glyphosates (24-32 oz). The list of pre-emergence herbicides in soybean includes: Axiom, Pursuit, Prowl, and Sencor/Lexone

Also, consult the label direction for additives and for the pre-plant and post-plant intervals. For example, corn should not be planted 5 days before or after application of 2,4-D. Also 2,4-D can be used for burndown in soybean but at least 7 days prior to crop planting. More details on these herbicides and their use rates can be also found in the University of Nebraska Guide for Weed Management. It is a publication that is updated annually; this year's version has lots of new features, a nice color cover page, and it can be purchased in every county extension office for the nominal fee of $3. (SK)