Pecan fungicide and insecticide applications have been frustrating due to uncooperative weather patterns. Below are some questions I have been getting from pecan growers.
What about this leaf scorch and anthranose I keep on hearing about?
I have had a couple growers bring in a couple leaf samples for diagnosis and results from the diagnostics lab have indicated anthranose and leaf scorch. Below is information from Andrew Sawyer, Area Pecan agent.
Leaf Scorch – There are a few things that maybe causing leaf scorch right now.
1) The first being bacterial leaf scorch is a common concern for pecan growers. It is more often found in Cape Fear, but not every single variety. This is a hot topic for growers since there are no spray remedies and a lot of concerns about how it gets in an orchard.
2) Anthracnose could also be a culprit. It is a fungal pathogen that infects late April/early May and doesn’t show up until…… now. It can defoliate some trees. Our current spray programs would target anthracnose, however I have noticed where growers have more serious anthracnose, they usually only have done two pre-pollination sprays (April – May). It is our goal to reduce pre-pollination sprays when weather is more dry. Two is a great number. It could be that in orchards with significant anthracnose, growers may have to do a third spray to make sure that period of infection is covered. A grower often calls with a description of, “It’s raining leaves in my orchard.” Usually late July and on into August when they see this.
When do we tissue sample our pecans? Now is a good time for growers to sample leaves in pecan for fertility requirements (July 7 – August 7). In the illustration below, you will see exactly which leaves to sample in the orchard. You need 50 middle pairs. Keep the varieties the separate. Collect leaves in the sunlight. They can be mailed in paper bags or those folders used for leaf samples. The lab runs it as a leaf tissue sample. With the current price of fertilizer combined with research showing how long pecans can store certain nutrients, these leaf samples may keep growers from broadcasting phosphorus and potassium next season. It will also show their zinc levels which is the best indicator if the trees are taking in zinc.
If you have questions please contact your local County agent.