A grand, old pecan tree in your yard is a wonderful anchor for the space, a good source of a large, shady patch, and of course a bountiful provider of tasty pecan nuts. But, if your tree gets struck with pecan phytophthora rot, a fungal infection, you could lose the entire harvest.
What is Pecan Shuck and Kernel Rot?
The disease is caused by a fungal species, Phytophthora cactorum. It causes rot in the fruit of the tree, turning the shuck into a mushy, rotted mess, and rendering the nuts inedible. The disease is most common after it has been wet for several days and when the temperatures remain below 87 degrees Fahrenheit (30 Celsius) during the day. Pecan shuck and kernel rot infections usually occur in late August or early September. The rot begins at the stem end and slowly covers the entire fruit. The rotten part of the shuck is dark brown with a lighter margin. Inside the shuck, the nut will be dark and bitter tasting. The spread of the rot from one end of a fruit to the other takes about four days.
Pecan Shuck Rot Treatment and Prevention
This fungal infection is not that common and tends to occur in only sporadic outbreaks. However, when it does strike, it can ruin half or more of a tree’s crop. It’s important to provide pecan trees with the best conditions for preventing the disease and to look for signs of it in order to treat immediately. The best prevention is to simply make sure the tree is trimmed adequately to allow for airflow between branches and around fruits. To control pecan kernel rot in trees that already have signs of the infection, a fungicide should be used right away. If possible, apply the fungicide before the shucks split. This application may not save every nut on the tree, but it should reduce the losses. AgriTin and SuperTin are two fungicides used to treat pecan shuck rot.
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FAQs
The best prevention is to simply make sure the tree is trimmed adequately to allow for airflow between branches and around fruits. To control pecan kernel rot in trees that already have signs of the infection, a fungicide should be used right away. If possible, apply the fungicide before the shucks split.
What is the best fungicide for pecan trees? ›
Miravis Top and Elast applied alone or in the combination of Elast/Tin will give you maximum protection of nuts as they are rapidly developing through the nut sizing stage. But there will be scenarios in which you may need to, or have the option to, use other materials.
How much zinc do you put around pecan trees? ›
Apply 3–6 lb/acre of zinc sulfate on bearing trees, 1–2 lb/100 gal water on nonbearing trees. Apply at least 3 times during spring and summer. Soil applications may be used in acidic soils. Apply 3–6 lb/acre of zinc sulfate on bearing trees, 1–2 lb/100 gal water on nonbearing trees.
What spray kills pecan weevil? ›
If you decide to use insecticide to control the pecan weevil, applications should be made every 7 days from mid-August through mid-September using a carbaryl (Sevin) insecticide.
How do you treat pecan fungus? ›
Use fungicides at the correct concentration. Sprayer calibration is essential for economical and effective use of fungicides. Spray: When leaves of disease susceptible cultivars are about one-inch in length. Leaf Scab, Vein Spot, Downy Spot Select from fungicide list.
What is a systemic fungicide for pecans? ›
Phosphorous acid has been shown to work well against both leaf and nut scab. Propiconazole (FRAC 3): The home garden fungicide Ferti-lome Liquid Systemic Fungicide II is available in small quantities and is labeled for use against scab in pecans.
What should I spray my pecan trees with? ›
Zinc Sulfate can be applied along with both fungicide and insecticide spray, which should be applied any time spraying is warranted. Zinc Sulfate will prevent rosetting in pecans along with keeping the leaves pretty and green. If they are not pretty and green, chances are the tree is lacking Zinc.
Is Epsom salt good for pecan trees? ›
If you have some fruit trees, a boost in magnesium will do them a world of good. Epsom Salt is used on fruit trees or vegetables to help them yield larger, sweeter, and more fruits. It works great also for nut trees and fruit shrubs.
What are the symptoms of zinc deficiency in pecan trees? ›
Zinc deficiency symptoms: (a) Rosetting caused by shortened internodes and (b) interveinal chlorosis and necrosis of young leaves.
Is 10-10-10 fertilizer good for pecan trees? ›
The main thing pecan trees need to produce nuts is nitrogen (the first number in fertilizer). If you are growing a tree or two in your yard, 10-10-10 might be a suitable fertilizer for you, but you'll need to apply Zinc separately.
Shuckworm. Shuckworms can be one of the more destructive pests of pecan. These are white worms that grow to 3/8 inch and tunnel in small nuts causing them to drop in July and August. After shells harden, larvae tunnel in shucks and prevent kernels from developing properly.
What is the best herbicide for pecan trees? ›
If you have more grassy weeds glyphosate will be the best option for the burndown material. If broadleaf weeds are more of an issue, go with paraquat or glufosinate.
How do you get rid of pecan worms? ›
For best control, apply insecticides after eggs hatch and before larvae develop dense webs. Insecticides containing acephate (Orthene®), Bacillus thuringiensis (B.t.), carbaryl (Sevin®), chlorpyrifos (Dursban®, Lorsban®), diazinon, malathion, and tebufenozide (Confirm® 2F) are effective. Insecticides containing B.T.
Why are my pecans rotten every year? ›
Most pecan diseases are caused by pathogenic fungi that remain dormant during the winter months on twigs, leaves, nut shucks, and bark, either in the tree or on the soil.
How much zinc for pecan trees? ›
When zinc deficiency symptoms are critical, apply 36 percent zinc sulfate to the soil at the rate of one-half pound per inch of trunk diameter with a maximum of 10 pounds per tree per year. Effectiveness of soil applied zinc decreases as soil pH increases above 7.0. Zinc may be applied via foliar spray.
What is the best fungicide for pecan scab? ›
Some fungicides like Phosphite and the group 3 + group 11 materials have better activity on leaf scab. Others, like Elast, Tin, and Miravis Top offer the highest degree of nut scab protection. There are also other labeled materials that could be worked into the schedule. The following is simply an example.
What does a diseased pecan tree look like? ›
The first sign of the disease appears in May and June. Circular, dark brown spots ranging from 0.12 to 0.37 inch in diameter appear along the midrib on the lower surface of the leaflets. In late summer, the spots turn a cinnamon brown or liver color.
How do you increase the yield of a pecan tree? ›
Irrigation provides a 70% increase in yield of mature trees (Daniel, 1982), and a 300% increase in growth of young trees (Wells, 2017). *If you receive 1” or more of rain from bud-break to the onset of kernel-filling, turn the system off for 3 days.
What is the most disease resistant pecan tree? ›
Probably the best known of this group is 'Elliot'. 'Elliot' has long been the standard by which we measure resistance to scab. 'Elliot' produces a small round nut with very good kernel quality.
When to spray pecan trees for scabs? ›
For commercial pecan orchards, the prevention of scab on susceptible varieties is straightforward. Trees must be sprayed every 14-21 days from budbreak to shell hardening with one of several EPA-registered fungicides to prevent leaves or nuts from damaging infection (Fig 1).
