Source: University of Arkansas
Wheat in Arkansas is considered a winter crop. As a result, the insects that attack wheat are oriented primarily to the fall and spring time periods. In the fall, the primary insects of concern are aphids, fall armyworms and the initial infestation of the Hessian fly. During the winter months, the Hessian fly will develop during periods of warmer weather and can develop into a serious problem in areas where wheat is produced every year and on the more susceptible varieties. The true armyworm and aphids are of concern in the spring. Armyworms are a problem in the state in late May and early June. Infestations of armyworms can reach high levels in some years and fields should be scouted during this time period. The consequences of the Hessian fly infestation will be evident by the presence of shorter stems, lodging and reduced yields when infestations are significant.
In the fall, fall armyworms may be a problem in seedling plants. Fall armyworms feed on the young plants and eat the plants to the ground, causing a loss of stand. Damage of this type may occur from emergence until a bad frost or freeze eliminates the threat of armyworms. Wheat will usually recover from moderate fall armyworm damage. An infestation level of five to six worms per square foot will justify treatment. Treat only during the warmer part of the day; most of the recommended materials have limited activity below 60 degrees F.
In the spring, true armyworms are a threat about the time heading starts to occur. Wheat is very attractive to the armyworm and thick, vigorously growing fields can attract high infestations. Occasionally, when wheat starts to mature, armyworms will move up from leaf feeding and cut the wheat heads from the plant stem. Since this type of damage can have serious consequences on yield, close field observations are required. Treatment should be made if head cutting is beginning to occur and armyworms are present. Scouting of fields for armyworm infestations should occur in the spring when wheat starts to grow vigorously.
Armyworm Control Recommendations
The armyworm may be controlled using registered insecticides. Refer to the University of Arkansas Insecticide Recommendations Guide (MP144) for the currently labeled insecticides. The best time to apply an insecticide would be late afternoon since the armyworm feeds primarily at night.
Wheat in the mid-south is attacked by four species of aphids. These include the greenbug, bird cherry-oat aphid and the corn leaf aphid. All of these aphid species may occur in wheat fields at any time during the production season. In addition to wheat, all the aphids attack a wide range of grass hosts including all the grain crops. Most aphids that occur on wheat will transmit the Barley Yellow Dwarf Virus (BYDV), however, the bird cherry-oat aphid is the most common vector of this disease in Arkansas . Preventing transmission of BYDV by controlling aphids is difficult to achieve using insecticides. Damaging BYDV outbreaks occur approximately 1 out of 10 years. Therefore, in any given year, controlling the aphids that year will only give you at best a 10 percent chance of preventing BYDV outbreaks with a significant potential to reduce yield. The most effective method of controlling BYDV is avoidance of early-planted wheat allowing infected summer hosts to die before wheat emerges, thus, reducing chances of aphid transmission.
To read more
Source: University of Arkansas