Backyard Orchard News
At least one on-line weather forecasting site is predicting rain for Aug 20-22. That is right about the time prune harvest may begin in the Sutter/Yuba area. The forecast could be mistaken, but it might be a good idea to make sure your sprayer is ready and you have the best program (fungicide, sprayer set up and calibration) ready if needed.
Sprays to protect prune fruit from brown rot must be applied before rain. Research by Dr. Jim Adaskaveg, University of California professor of plant pathology, has shown the following materials and application practices to provide the best possible protection:
Best Materials (++++) in the 2011 UC Fungicide Efficacy and Timing publication followed by fungicide class (in parenthesis) appear below. Dr. Adaskaveg advises growers not to use the same fungicide chemistry more than 2 times in a single growing season. Check the label, consult with your packer and PCA before applying a fungicide preharvest.
- Bumper/Tilt (3)
- Indar (3)
- Quash (3)
- Pristine (7/11)
- Quilt Xcel (3/11)
Complete information at: http://www.ipm.ucdavis.edu/PDF/PMG/fungicideefficacytiming.pdf
I strongly suggest growers talk with their PCA about tank mixing two chemistry groups if allowed by the label and a premixed material has not been selected. For fruit brown rot control, Group 9 materials are rated +++ (good and reliable) by Dr. Adaskeveg compared to ++ (moderate and variable) for Group 11 materials. Group 9 materials should provide better resistance management support of Group 3 materials for fruit brown rot control than Group 11 materials.
Best results with research by Dr. Adaskaveg on prune fruit brown rot control include the following practices:
- Adding 1-2 gallons of 415 weight summer oil for each 100 gallons of spray water in the tank. Use of 440 weight oil instead of 415 oil may provide similar results, although this has not been tested. 440 weight oils are labeled for summer use, but max rate is 1 gallon per 100 gallons. Check the label of the oil product before spraying. Make sure there is NO sulfur in your spray tank (or sprayer filters) before adding oil to the tank.
- Using high spray volume ( for example 160-200 gallons/acre)
The most difficult spray job of the season is preharvest, when the canopy is most dense and weighed down by the weight of the crop. Slow tractor speeds will deliver the best spray coverage under these conditions. Slow down and do the best job possible.
Aerial application will provide less control than careful ground application.
Finally, lower your expectations. Fruit brown rot control preharvest is difficult. This is especially true when conditions (warm and wet weather + clustered fruit) favor infection. Complete control may not be possible.
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Fuller rose beetles are a primarily a problem because they lay eggs under the calyx of fruit and those fruit can be rejected when exported, because some export countries don't want this pest to establish in their region. Fuller rose beetle can also cause significant leaf damage to newly topworked orchards. We have been sampling an orchard near Lindcove and, while a few beetles emerge year round, we are seeing heavier numbers emerging as of the first week of August. You can find Fuller rose beetles first by looking for notched leaves (edges chewed) and frass (insect feces), then look for the adult beetles inside curled leaves. They love new flush and leaves rolled by leafminer damage. They tend to be on the lowest branches of the tree. You can also survey for them by putting a beating sheet or tray under the trees and shaking the adults out onto the tray.
Fuller rose beetle on notched leaf
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