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Thursday, March 25, 2010

Strawberry update and chilly weekend weather

Mite trial plots at the Central Crops Research Station. Plants were sourced from Aarons Creek Farms, Buffalo Junction, VA and made it through the cold winter with flying colors.

Today, we sampled our plots at the Central Crops Research Station in Clayton, NC for the 3rd time this season. Spider mite populations remain low, but we will begin calendar treatments for our threshold validation trial next week. This trial is comparing treating at threshold levels versus treating on a calendar basis. Specifically, we are comparing the following treatment regimes:

1. Untreated control
2. Frequent treatment (every 14 days)
3. Infrequent treatment (every 45 days)
4. Treatment at recommended threshold (5 TSSM/leaflet)
5. Treatment at reduced threshold (2 TSSM/leaflet)

Most plants have 2-5 blooms open, which means we plan to begin harvest in about 45 days, mid May. Strawberry plantings throughout NC are about 2 weeks later than normal.

We are assessing mite densities weekly and will also collect data on brix in the different treatments. Growers have been curious as to whether TSSM densities below yield reducing levels (our working threshold of 5 motile mites/mid tier leaflet) also reduce fruit quality, and the quality measure of greatest concern is brix. Last year, we conducted a similar trial with an organic cooperator and saw no correlation between brix and mite densities or mite days (a measure of mite density over time). This year's trial will be conducted with conventional miticides.

In addition to the threshold validation trial, we will also be conducting efficacy trials with conventional miticides, some of which are newly registered for strawberries.

Frost is called for this weekend throughout NC, and our plots were covered with floating row cover this afternoon. Dr. Barclay Poling, NCSU Horticulture, regularly posts updates on weather conditions and other production considerations at the NC Market Ready Strawberry Grower Information Portal. The latest update shares information on the upcoming cool weather as well and some pest management points from me regarding bloom and insecticide use.

Temperature maps from Envirsion, a weather modeling group based in Raleigh, illustrate the frost potential throughout NC for this weekend.

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