Healthy fields bring higher yields but may also serve as beacons for hungry insects. Although the worst U.S. drought since 1956 caused pastures and crops to deteriorate, it also left fewer host plants and fall crop stubble for insects to feed on.
Aphids that feed on infected host plants and crop stubble, can carry the devastating barley yellow dwarf virus (BYDV) to wheat planted this fall. With a few more weeks of winter wheat planting left, there is still potential for fall aphid pressure to creep up on growers. To reduce risk, it’s important for growers to be proactive and protect their crops from the start, enabling them to grow more wheat and achieve higher profits.
Although the 2012 drought may have decreased the potential for fall aphid pressure, it only takes one aphid to transmit BYDV to a field. There are multiple species of aphids, but only certain species transmit BYDV. Most common of the BYDV-transmitting aphids include the bird cherry-oat aphid, corn leaf aphid, English grain aphid and Greenbug.
Aphids contract BYDV by feeding on infected host plants, and then BYDV is spread as infected aphids feed on healthy plants. This virus can cause underdeveloped root systems, plant stunting, winterkill, decreased tillering, delayed maturity, nutritional disorders and reduced grain quality and yield.
Researchers have identified that the fall population of aphids has the greatest potential to vector BYDV and leads to the most dramatic decrease of yield in the spring. If growers are not proactive in ensuring their crops are protected this season, this tiny insect can have a devastating impact on yield by vectoring BYDV.
Eliminate the Green Bridge and scout fields
First and foremost, researchers and agronomists recommend delaying fall planting, eliminating the green bridge and diligently scouting fields.
With the drought this year, delaying planting until the later part of the planting window may allow for more moisture, and it can also help growers actively prevent aphid infestations. Later fall planting dates are recommended to give aphids less time to transmit the virus before cold temperatures set in.
Agronomists also suggest eliminating the green bridge by controlling green residue in the field. This residue will act as a “bridge,” connecting infected aphids to the new crops and allowing for the spread of BYDV.
“We recommend that growers destroy any green residue with a burndown application of a herbicide at least two weeks before planting begins to eradicate the green bridge and break pest cycles,” said Les Glasgow, herbicide technical asset lead, Syngenta, who noted the company has choices to accomplish the task.
Get an insurance policy
Prevention is key with BYDV. Scouting aphids in the fall is an extremely difficult and lengthy process, and by the time aphids are spotted in a field, it’s likely the infection is present already, too. A grower’s best option is to prevent aphids from attacking in the first place with a quality seed treatment, according to Syngenta. The right seed treatment can protect cereal crops from fall aphid attacks and serves as a first line of defense against BYDV.
“You don’t know for sure if you are going to have an aphid or BYDV problem before the planting season. But, you do know that if you apply a seed treatment, you are virtually eliminating the risk,” said Jim Swart, extension specialist, Texas AgriLife Extension. “Seed treatments help ensure you don’t end up with BYDV. In effect, it is basically an insurance policy.”
Like any good insurance policy, a seed treatment offers full protection from yield-robbing insects from the moment seeds are planted, working systemically to protect plants as they grow. Even if there is little or no aphid pressure this fall, thiamethoxam active ingredient seed treatment has been proven to produce healthier, more vigorous plants.
This season, Syngenta is also suggesting growers can achieve added seedling protection with the right seed treatment fungicide, which is fully compatible with insect protection seed treatments and protect wheat and barley seedlings from diseases and insects at the same time.
A combination of three active ingredients--sedaxane, mefenoxam and difenoconozole--is in Vibrance Extreme fungicide, which protects against a broad spectrum of seedborne and soilborne diseases, explained Chad Shelton, seedcare brand asset lead, Syngenta.
Protect in the spring, too
Fall aphid attacks may be the most devastating, but aphids can cause significant damage in the spring, too. As the year goes on and spring emerges, growers should continue to be proactive against aphids with diligent scouting. If aphids are present, a foliar insecticide application labeled for aphid control may be warranted. The foliar insecticide used for spring aphid attacks should be able to be tank mixed with most herbicides and fungicides to save trips across the field, Syngenta points out. The company also says agronomists, consultants or growers should check with their state or local Extension office for aphid threshold level spraying recommendations in an area.
While the drought of 2012 may be keeping aphids at bay for now, fall conditions can change quickly into those favored by this yield-robber. At the start of the season, there needs to be time invested to protect wheat by delaying planting, eliminating the green bridge and scouting fields. Continued scouting in the spring, as the weather warms up, is necessary to keep aphids from causing major damage at this point, too. Ultimately, an integrated approach that includes scouting, sound management practices and quality seed treatments and crop protection products will help ensure a healthy, pest-free crop with maximum yield potential.