Rhode Island Apple IPM
May 11, 2011: Recorded Apple Pest Message in Print

Hello Fruit Growers May 11, 2011
McIntosh trees are still in bloom in the Greenville area, while many trees in Newport County are just beginning to bloom.
I did find some apple scab on unsprayed apple trees yesterday. The scab lesions were on the underside of fruit cluster leaves, exactly where I expect to see first lesions of the season. These lesions are probably from the April 23rd infection period – which was probably the first major infection period of the season. It generally takes about 2 weeks for lesions to appear after an infection period. Orchard Radar predicted apple scab lesions would be visible on May 7 from the April 23rd infection period. Check now for scab lesions, especially if you feel your trees were not well protected for that infection period. Look on the underside of the fruit cluster leaves. Lesions could be on the smallest, oldest leaves, but also on the next larger leaves. If you find lesions, consider applying full rates of Captan or Syllit to try and kill spores developing in the lesions. Burning out lesions is very difficult and often impossible, that is why you work so hard keeping scab out!

As I mentioned, Orchard Radar is up and running, thanks to Glen Koehler at the University of Maine. Orchard Radar takes our SkyBit weather data and runs many models so we can predict thing events – like when scab lesions appear, or when primary scab season is over, or when various insects are around. It is really quite wonderful! You can access Orchard Radar from the RI Apple IPM website at http://www.uri.edu/research/ipm Choose Greenville or Newport County and then look at the different predictions on pests and horticulture. There are also models to help time thinning applications.
Another predicting tool is NEWA from Cornell and can be found at http://newa.cornell.edu/ At the NEWA site you select Pest Forecasts and then select the location. For RI, weather data is for Providence and Newport and is listed about 2/3 of the way down the list. I just looked at oblique banded leafroller and it states, “Pest Status: Emergence of overwintering larvae is completed by the end of bloom
Pest Management: Larval populations can be monitored by sampling blossom clusters. Bt can be applied during bloom if larval populations exceed threshold levels. All other insecticides cannot be applied until petal fall.” If you change the time to Petal Fall, you can see the recommendation for petal fall against oblique banded leafroller. It’s really slick and worth investing some time with both Orchard Radar and NEWA.
Orchard Radar predicts 95% McIntosh petal fall on May 14. Soon after this is the time for a petal fall insecticide application to control European apple sawfly, plum curculio and other insects. Most growers will apply Imidan, but some growers are moving away from Imidan and applying Avaunt or Calypso.
Now is a good time to look for European red mites on the underside of cluster leaves. The best clusters to look at are ones close to large limbs. These clusters will have the most red mites at this time of the year. If you find your mite population is above the threshold of one mite per leaf, consider applying a miticide at petal fall. Miticide choices at petal fall include Apollo, Savey, Onager, Zeal and Agri-Mek.
I am seeing more winter moth caterpillars in orchards, but not in large numbers. Winter moth caterpillars are about ½ an inch long now and have long, pale stripes down the length of the body. In this picture you can see two prolegs at the back of the caterpillar. Winter moth caterpillars have two sets of prolegs while most other caterpillars have more. At this time, the caterpillars are feeding primarily on leaves and may be found in leaves tied together with their silk. The caterpillars will be around for a couple of more weeks and then they will drop to the ground to pupate. They’ll remain in the soil until November when the moths emerge.

I expect to see every one of you at next week’s twilight meeting at Narrow Lane Orchard in North Kingstown. The meeting is May 19 at 5:30 at 213 Narrow Lane. Give me a call if you have questions – 874-2967 or 256-7438.