A website from UGA Cooperative Extension

Pecan sprays in our area have already began in some orchards and will soon be starting in most others. The optimum temperature range for scab infection is 59-77 degrees F and a leaf wetness of about 12 hours. Our temperatures are right and rain is in the forecast which means the weather is almost perfect for scab.

Pecan spray suggestion guide for 2016 is the same as the past two years:

1. Absolute

2. Tebuconazole+Topsin M+Phosphite

3. Absolute+Phosphite

4. Elast/Tin

5. Absolute

6. Elast/Tin

7. Elast/Tin

8. Elast/Tin

If rainfall during the growing season is excessive, more than 8 sprays will be required for management of scab on susceptible cultivars, therefore, the following program serves as an example of how to accommodate this need.

1. Absolute

2. Tebuconazole+Topsin M+Phosphite

3. Absolute+Phosphite

4. Elast/Tin

5. Absolute

6. Elast/Tin

7. Elast/Tin

8. Quadris Top

9. Elast/Tin

10. Elast/Tin

Here is another spray program example:

httpsite.extension.uga.edupecanfiles201404Fungicide-Schedule-Example.pdf - Internet Explorer 4182014 110014 AM

These examples serve only as possible options for fungicide programs to manage scab. Many more could be developed. If an orchard has a documented high level of insensitivity to any of the fungicides, the grower should contact the local UGA Extension Agent.

Pre Emergent Herbicides

Most all growers have applied a herbicide in the orchard by now. How can you keep the herbicide strip weed free and limit the number of applications needed?

  1. Include pre-emergent herbicides in your program. Alion is an excellent pre-emergence material that gives long lasting control. It has a high price tag but it will significantly cut down on the number of applications you need to make. Use the 5 oz/A rate in the first year that you use Alion. After that, you can drop down to the 3.5 oz/A rate. Alion is labeled for trees 3 yrs of age or older. However, that label will likely soon be changed and this material would then be labeled on 1st year trees and older. UGA has tested it for a number of years on 1st year trees at high rates and have never seen a problem.
  2. Flumioxazin (Chateau) is also an excellent pre-emergence herbicide for use on trees from the 1st year on up. It doesn’t last as long as Alion, but it’s still a good choice. Rotation between Alion and Flumioxazin from one year to the next is a good idea to manage resistance and limit the over-use and buildup of indaziflam (Alion) in the orchard.
  3. There are many other options for pre-emergence which can be utilized in pecan orchards. These include Surflan, Simazine, Prowl, and Diuron. Isoxaben (Trellis) and rimsulfuron (Metric, Solida, and Pruvin) are recent additions to this arsenal. Of these, Surflan, Prowl, Isoxaben and Rimsulfuron can be used on 1st year trees and up. Trees must be 2 yrs old for Simazine and 3 years old for Diuron. Also, do not use Diuron on sandy soils. Consult the current UGA Pecan Spray guide here for a complete list of herbicides available for pecan and their uses.
  4. Tank mixing burndown and pre-emergent herbicides will reduce the number of trips made over the orchard, but be sure to have at least 75-80% bare ground when using a pre-emergence material. Most of them need good soil contact to be effective.

Contributors:

Dr. Lenny Wells

Posted in: