Pecan

Keep water on the tree through shuck split

Do not back off watering once the kernels finish filling. Keep the soil moist through nut maturity and shuck split, easing off only about a week before you plan to shake the tree. Shuck dehiscence - the shuck actually opening to release the nut - is a process that requires adequate water. A tree carrying a heavy crop on dry soil gets shuck decline instead, which delays or prevents the split and opens the nuts to anthracnose. Stick-tights that never release are the usual result.

Feed pecan by soil testMar – Apr

Apply nitrogen and zinc only as needed from soil or leaf tests, keeping fertilizer away from the trunk. Pecans have high nutrient demand, but overfeeding wastes money and can worsen disease or weak growth.

⚠ Follow local extension rates for tree size and soil results.

Foliar zinc: first spray at budbreak, then twice more

Starting at budbreak, spray the new growth with zinc sulfate at 2 to 3 pounds per 100 gallons of water. Repeat for three sprays total at 2 to 3 week intervals while shoots are still expanding. Young and fast-growing trees need this most. Pecans are heavy zinc users, and zinc is immobile in the tree - it only enters the leaves that are actively expanding when you spray. Miss that window and the shoots rosette with short internodes and small crinkled leaflets, and the deficiency cannot be corrected later in the season.

⚠ Soil-applied zinc only works where soil pH is below 6.0, and even then foliar application is far more effective. Above pH 6.0 soil zinc is locked up and wasted.

Dormant pruning: train a central leader, cut out narrow crotches

While the tree is leafless, train young trees to a single central leader and keep the lowest scaffold limbs at about 6 feet - head high or a little above - so you can walk and mow under the tree for the rest of its life. Remove branches with crotch angles narrower than 60 degrees now, while they are small. Mature pecans are not routinely pruned - thin crowded limbs and take out damaged wood only. Narrow crotch angles trap included bark and never form a real wood union, so they split out of the tree decades later under wind and a heavy nut load. Pecans get very large, and a crotch you ignore at year three is a crane job at year thirty.

⚠ Do not apply wound sealer. On cuts facing the afternoon sun, paint the wound with white latex paint to keep the tissue cool so it can heal over. (Wound guidance per UGA Pecan Extension, 'Pruning of pecan trees can be done at any time', 2017/04.)

Scout pecans for nut casebearerMay – Jun

Check small nut clusters for tiny white eggs or entry damage near late May and early June. Pecan nut casebearer larvae can destroy nutlets before the crop sizes up.

⚠ Treat only when scouting or local extension alerts justify it; follow label directions.

Phylloxera: spray at budbreak, before shoots reach one inch

If this tree had galls on leaves or twigs last year, spray imidacloprid or carbaryl at budbreak and again 7 to 10 days later. The window closes once new green growth passes about one inch. Phylloxera nymphs hatch at budbreak and feed on the tender shoot, and that feeding is what makes the tissue swell into a gall. Once the gall closes around the insect it is sealed inside where no spray can reach it, so a treatment applied after galls appear does nothing.

⚠ Treatments applied after galls begin to form will not work - do not spray later hoping to catch it. Imidacloprid is applied once per year at most, and trees treated with it are more prone to mite outbreaks.

Pecan scab: cover sprays through nut sizing until the shell hardens

On a scab-susceptible cultivar, spray boscalid plus pyraclostrobin or phosphorous acid once the nuts begin sizing, and repeat every 2 to 3 weeks depending on how often it rains. Continue through shell hardening. Rotate between FRAC groups rather than repeating one product. On a resistant cultivar like Elliott, Excel, or Kanza you may need no sprays at all. Scab only infects tissue that is still actively growing, and it needs free moisture from rain or heavy fog to germinate. That is why the spray has to be on the nut before the rain arrives, not after - and why rainy stretches during nut sizing shorten the interval.

⚠ Propiconazole is labeled only for nonbearing nut trees that will not produce a crop for at least 1 year - do not use it on a bearing pecan. Sulfur has generally poor efficacy against pecan scab. Never spray a pecan with a sprayer previously used for herbicide.

Pecan weevil: trunk sprays once the shell hardens and weevils emerge

After the shells harden and the kernels reach the gel to dough stage, watch for emerging weevils, especially in the days after a soaking rain. When they appear, spray carbaryl or bifenthrin over the lower 8 feet of the trunk and the ground beneath it, and repeat two to four more times at 7 to 10 day intervals until emergence stops. A 12 to 18 inch band of cloth smeared with Tanglefoot around the trunk also traps climbing adults. The female weevil cannot lay eggs in a nut until the kernel has gelled, so she waits underground and emerges when rain softens the soil enough to dig out. Timing to that emergence, not to a date, is the whole game - in a dry year they may not emerge at all.

⚠ Carbaryl and bifenthrin kill the predators of aphids and mites and routinely trigger outbreaks of both. Trunk sprays reach only the lower 8 feet, so they will reduce but not fully control weevils on a tall yard tree. Follow the label rate and preharvest interval on the product you buy - the label is the law. Soil-applied imidacloprid does not control pecan weevil.

Scab sanitation: rake and destroy fallen shucks and leaves before buds swell

After harvest and before the buds begin to swell in spring, rake up and destroy every fallen leaf, shuck, and leftover nut under the tree. Do not compost them in place under the canopy. Prune out damaged twigs while you are there. The scab fungus overwinters in last year's fallen leaves, shucks, and nuts, and those are the primary source of the spores that infect new growth in spring. Clearing the litter removes the inoculum before it can be splashed back up into the canopy.