West Central Michigan vegetable regional report – May 14, 2014
Crop progress has been slow in West Central Michigan, but pests are becoming active.
Common asparagus beetle adults were sighted in the Oceana and Mason County area by crop consultants last week. Adults of this pest lay eggs on the tip of spears, which are a contaminant during the harvest season. There are a variety of products available for control including generic carbaryl and Sevin (PHI one day, a.i. carbaryl), and Ambush, Perm-UP and Pounce (PHI one day, a.i. permethrin).
With recent wet weather, infection of spears by Phytophthora asparagi may also occur. Check fields with a history of this disease for signs of infection, including water-soaked lesions at the base of spears where inoculum splashed onto shoots. Infected spears may also form a shepherd’s crook and ultimately shrivel and die. If you see these shepherd’s crooks in low spots, it could be Phytophthora.
A pair of cutworm species – the white and dark-sided cutworms – could also be active. The white cutworm is active first as it overwinters as a larva. Caterpillars will climb spears at night to damage spear tips. The dark-sided cutworm overwinters as an egg and is active later. Its larvae feed at the base of spears. This can cause the undamaged side to grow faster than the damaged side, resulting in a shepherd’s crook. If you did not apply Lorsban (chlorpyrifos) at lay-by or are seeing damage, products you apply for asparagus beetles can provide control (permethrin formulations).
Flea beetles were active in cole crops in Ottawa County this week. Adults of this pest are complex – there are multiple species – and overwinter in hedgerows and headlands and enter fields in the spring. Controlling early season weeds in the mustard family can help reduce problems with this pest, who does its main damage by feeding on leaves of very young plants. Spunbond row covers placed over the crop at planting can reduce damage, and for conventional growers there are a variety of labelled insecticides should damage become severe enough to be economic.
Onions were in the flag and loop stage in Ottawa County earlier this week. According to Michigan State University Extension, now is a good time to consider what products you will purchase for your onion thrips control program. One lesson from last year: growers reported that starting the spray program early with Movento (a.i. spirotetramat) provided them with at least two weeks of control, allowing them to skip one to two sprays. If you use Movento, use it early as it is most effective against immature thrips, which are more prevalent early, and make sure to include a non-ionic, penetrating surfactant or a methylated seed oil. In addition, avoid tank-mixing it with fungicides containing the active ingredient chlorothalonil as this compromises its efficacy.
Black cutworms were captured in sweet corn this past week in traps in Montcalm County to our east. Killing broadleaf weeds through mechanical or chemical means will make your fields less attractive to egglaying females, helping prevent later problems with this pest.