Current Western NC Orchard Pest Populations Weekly Summary, June 29 2015
We track local insect populations throughout the growing season using a system of traps, temperature-recording devices, and degree-day models. Traps and weather data are checked weekly, with results updated by Tuesday afternoon from April through September. Learn more about southeastern apple pests at the Apple Pest Management page.
JUNE 29, 2015
We are currently in a period when there are relatively few insect pests that pose a threat to apples. Codling moth populations in lower elevation orchards, and, as discussed in last week’s pest news post, emergence of first generation plum curculio may be a concern in orchards that experienced significant damage earlier in the season.
Codling Moth: Depending on location, second generation codling moth is either in full flight or will be emerging in the next week. Insecticide sprays are based on degree-day accumulations, abundance of moths indicated by pheromone trap captures, and the level of damage caused by first generation larvae. Under very low population densities, usually when mating disruption is being used, no insecticide sprays may be necessary. Under high population densities, one or two well-timed applications are often necessary. See page 32 of the Apple IPM Guide to determine the need for second generation insecticide sprays. The choice of insecticide to use should be based on what was used to manage the first generation – choose an active ingredient effective against codling moth but not used against the first generation. For instance, Altacor (a.i.= chlorantraniliprole) and Delegate (a.i.= spinetoram) are two different insecticides commonly used for control of codling moth. In those orchards that sprayed Delegate during the first generation, Altacor should be applied during the second generation, or vice versa.
In higher elevation orchards in such as Henderson County, only about 1200 DD have accumulated since biofix, so in this area we are still at least 7 to 10 days from the beginning of moth emergence. In lower elevation orchards in the foothills and piedmont (e.g., Alexander, Wilkes, Cleveland, Lincoln and Polk Counties), codling moth degree-day accumulations range from about 1500 to 1650, which is equivalent to emergence of about 50 to 75% of second generation moths. Close attention should be paid to pheromone trap captures and an assessment of damage caused by first generation larvae.
In general, codling moth pressure has been fairly low this year, so in most situations a single insecticide application is provide sufficient control, but all decisions should be based on moth activity as measured by pheromone traps.
European Red Mite: European red mite still remains a threat in orchards that have not experienced problems as of yet. Typically, if ERM have not developed to problematic levels by the first week of July, populations will remain low for the remainder of the year in most instances – assuming that pyrethroid insecticides harmful to natural enemies are not used.
Average Weekly Trap Captures*
|Insects per trap|
|June 15||June 22||June 29|
|Oriental Fruit Moth||2.8||2.5||4.3|
|Tufted Apple Bud Moth||8.5||3.5||1.5|
|Brown Marmorated Stink Bug||0.3||1.5||0.8|
|Spotted Tentiform Leafminer||23.0||57.0||27.0|
|Lesser Peachtree Borer||53.5||42.0||31.0|
|San Jose Scale||0.0||1527.5||7675.0|
*Note that averages presented here are intended only to illustrate the timing of insect emergence and fluctuations in population activity, and not as general indicators of population levels. Some orchards included in these averages have significantly higher or lower populations than most commercial orchards in the area, resulting in averages that are sometimes skewed from what is typical. The only way to have an accurate assessment of an individual orchard’s populations is to set up traps in that orchard.
Accumulated Degree Days
|Codling Moth||April 23||828||1012||1176|
|Oriental Fruit Moth||Apr 6||1330||1544||1771|
|Tufted Apple Bud Moth||April 23||1070||1284||1476|
|About degree-day models:The degree day (DD) models predict adult emergence and egg hatch of each generation. They do not predict the intensity of populations, which can be assessed by using pheromone traps. Hence, the models should be used to help gauge the time period when control is most likely needed, and pheromone traps provide information on the need for and frequency of insecticide applications. For full details, read “IPM Practices for Selected Pests” in the Orchard Management Guide.|
|ORIENTAL FRUIT MOTH:
| TUFTED APPLE BUD MOTH: