Codling moth management 5/28/19
Many growers in RI have had problems with codling moths the last couple of years. It seems as though codling moths are resistant to Imidan. Here are a few basic things to know to help you manage codling moth:
- Adult codling moths start emerging between McIntosh bloom and petal fall and continue emerging for about 40 days. Peak emergence is usually in late May. Female moths start depositing eggs on leaves soon after emerging. Eggs hatch in 7-8 days.
- Insecticides are aimed primarily at newly hatched larvae before they enter fruit. So first insecticide application is generally around 2nd cover spray, or 250 degree days (base 50) after McIntosh petal fall. (Some models say 220 DD, but these numbers are approximations.) Here are degree days for Greenville since 5/15/19, the date of McIntosh petal fall. The numbers in red are the predicted degree days.
|Greenville||May 15||May 16||May 17||May 18||May 19||May 20||May 21||May 22||May 23|
|DD for day||0||7||8||11||8||20||10||8||6|
|May 24||May 25||May 26||May 27||May 28||May 29||May 30||May 31||June 1||June 2|
|June 3||June 4||June 5|
So in Greenville at the end of the day on 5/27/19, we were at 140 DD. And it looks like we’ll reach 220 DD on June 4, and 250 DD about June 6th. These numbers change with the actual weather we get.
Trees in Newport County are behind those in Providence County. McIntosh petal fall was about 5/19/19, so we have accumulated a total of only 9 DD since petal fall (since it was yesterday). An insecticide treatment in Newport County for codling moth will be later than in Providence County.
The following 3 pages review insecticides for managing codling moths. This information is from Michigan State University.
- Around mid-July, codling moth larvae leave fruit and pupate. Second generation adult moths start emerging in late July and continue emerging through August. Eggs laid by this generation tend to cause more damage than the first generation. I’ll send information on timing to manage the second generation larvae later this season.