Wheat is greening up in spite of the rollercoaster weather. Producers have been and are busy applying fertilizer and herbicide. Most of the wheat, except for late planted fields looks fair to good. Some areas of winter kill have shown up, nothing widespread but fairly small areas and being a bit more common on the sandier ground. Wheat would typically be closer to jointing now but that isn’t necessarily a bad thing as it regards damage from a late season freeze. Aside from needing some timely rain, is there anything else for producers to be concerned about and pay attention to over the next several weeks? Of course – insects. So what should producers be on the lookout for this spring? For descriptions on the appearance of these pests, please refer to http://www.ksre.ksu.edu/p.aspx.
• Bird cherry-oat aphid – This is the first aphid to become active in the spring and one of the larger ones (1/16”). On the plus side, its feeding does little direct damage although heavy feeding may reduce grain yield and quality. In the spring, treatment is usually unwarranted unless populations reach more than twenty per tiller at the boot or heading stage. Often beneficial insects help keep their numbers in check. The problem with this aphid is its vectoring of the barley yellow dwarf virus which can have significant effects on yield. Spraying has little effect on stopping the virus spreading. While yields can be decreased by fall infection up to 35%, as the aphids infect the wheat later, yield losses decrease until almost negligible when occuring at heading. There is no fungicidal treatment for infected plants.
• Army cutworm – Typically a pest late fall to early spring but outbreaks are extremely hard to predict field to field. This caterpillar has been a problem the last two years in central Kansas. They feed during the winter when temperatures are a bit above freezing. They only feed above ground and infested fields have a grazed appearance. Fields that never green up in the spring may be infected and fields should be checked through early April. Late planted wheat and wheat under less than desirable moisture conditions is most vulnerable. An actively growing stand with many tillers can withstand a great deal of feeding without yield loss and outgrow the problem. A density of four to five worms per square foot may require treatment, especially for stressed wheat.
• Armyworm – Another caterpillar but one doing most of its damage in eastern and southern Kansas so this area is on the edge and can see damage. They feed mostly at night while the weather is warm and moist from mid-April through early June. Treatment normally isn’t justified until populations are above five worms per foot. As wheat matures, this worm will migrate into adjacent corn and sorghum field.
There are a few others but these are the major concerns for our area. For more information, contact you area extension office or the extension entomology website.