Codling moth remains the key concern among insect pests throughout the region, but it is also time to begin tracking tufted apple bud moth activity.

Codling moth degree-day (DD) accumulations as of 12 May range from about 360 to 570 in higher (>2000 ft) and lower elevations (about 1000 ft), respectively. The cool temperatures, especially at night, over the past 5 days and expected for the next few days, have suppressed flight activity and egg laying. However, activity of both is expected to increase with the return of warmer temperatures this weekend. Historically, the most intense period of pheromone trap captures often occurs between about 350 and 700 DD, so pheromone trap monitoring will be especially important over the next few weeks to gauge the intensity of populations in individual orchards.

In orchards with historically low populations, most often but not always associated with annual use of mating disruption, it is possible to avoid spraying for codling moth throughout the entire first generation. However, an insecticide timed for tufted apple bud moth (see below) will occur over the next several weeks, and choosing an insecticide effective against both will provide a level of added protection.

In the 1990s the TABM was the most damaging pest of apples in NC due to resistance to organophosphate insecticides. With registration of the lepidopteran-specific insecticide Confirm in 2000, and additional insecticides for lepidopterans since, TABM has been relegated to minor pest status. Where once as many as 4 or 5 insecticide applications were necessary for TABM control, since 2000 one well-timed insecticide application provides excellent season long control. However, TABM still lingers in the background, and if ignored it can quickly reappear and cause damage.

A degree-day model similar to that for the codling moth was developed to predict first generation egg hatch. Degree-days are accumulated from biofix, which like the codling moth is designated as the first capture of a moth in a pheromone trap. Studies have shown that the window of opportunity for excellent control extends from about 700 to 1200 DD, a period of about 3 weeks. That timing also coincides with about 500 to 700 codling moth DDs, so an application of an insecticide effective against both TABM and codling moth at this time provides season-long control of TABM and is usually the last insecticide needed for first generation codling moth.

TABM DD accumulations currently range from about 490 in Henderson County to 750 in Cleveland County. An application in lower-elevation orchards anytime between now and the next 10-14 days is ideal.  In Henderson County and similar elevations, we are still about 10 days away from when the TABM window opens.

Those products providing excellent TABM and codling moth control include:

• Spinosyns (MOA group 5): Delegate
• Ecdysone Agonists (MOA group 18): Intrepid*
• Diamides (MOA group 28): Altacor, Exirel, Verdepryn
• Isoxazolins (MOA group 30): Zivalgo

*Note that Intrepid 2F will provide excellent control of TABM at only 8 oz/acre, but 16 oz/acre is recommended for codling moth. 

Learn more about southeastern apple insect pests at the Apple Insect Management page.

About degree-day models