Young Trees
All of our pecan fungicides have begun at this point. We have lots of newer planted trees in the county, here are some being sprayed last week. UGA Extension Horticulturalist Dr. Lenny Wells says trees in the first few years need to be sprayed but not on a detailed spray program. For very young trees, a few fungicide applications in a season with some Tin is good. Once the trees approach production age, we need to add a few more sprays throughout the season and get closer to a full spray program.
Timing
In our area, we have been hit so hard with scab that we tend to get our fungicide sprays out real soon. Dr. Wells always says we can wait a little longer than we do. He was down last week looking at a fertilizer situation, and we looked at trees around that were leafing out at different times. He explained the issue with spraying early is not having enough leaf area for the fungicide to contact.
The most difficult part is managing orchards for more than one cultivar, which all are pretty much the same. If Desirables are in the orchard, we have to begin spray on their schedule since they are more susceptible for scab. If an orchard doesn’t have desirables and mostly Stuart, you can wait until those leaves come out. Here is a few pictures of optimum fungicide initiation Dr. Wells and I looked at in an orchard last week.
Left – This is time to spray Desirable
Right – This is too early for Desirable
Optimum time to initiate Stuart fungicide sprays
Fungicide Schedule
Below is an 8-spray fungicide schedule from UGA Extension Horticulturalist Dr. Lenny Wells provided as an example to use for pecan scab management in light of emerging scab insensitivity issues surrounding some fungicides. Since Tin is an integral part of our fungicide arsenal for pecans, and we do see some orchards with insensitivity to Tin, we are recommending saving any Tin sprays for the nut scab period since this material is better on nut scab than it is on leaf scab.
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
These examples serve only as two 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 listed above, the grower should contact one of the UGA Extension for specific recommendations.
Thomas County Ag 