Question
We moved into our new house last July. We are located in N.Central Texas.  The two mature pecan trees were fully loaded with pecans but when they fell they were either dried up or wormy.  I noticed a small hole in the green hull of all the pecans still on the tree.  What is wrong with them and how can we control it this year. Thanks

Answer
Sounds like pecan weevils. Here is some information on pecan weevils from the Texas Extension Service. I would suggest you contact them at the local level and ask for assistance. Some trees are just too large for most homeowners to spray and you may need the help of a [professional sprayer (ask the extension Service for their advice).

The pecan weevil is the most damaging late-season pest of pecans where it is found in Texas. Infestations are often localized and vary a great deal within orchards.

Damage: Adult weevils begin to emerge from the soil in August and feed on nuts in the water stage, causing them to drop. After the kernel has entered the dough stage, the nut is susceptible to egg laying and attack by pecan weevil larvae. Infested nuts remain on the tree while the developing larvae consume the kernel. Full-grown larvae chew a round hole through the shell and emerge from the nut in late fall or early winter.

Biology: The life cycle of the pecan weevil - egg, larva, pupa and adult - usually is completed in 2 years but can require 3. Adult weevils begin emerging from the soil in August; their numbers peak from late August through early September. Rainfall, soil moisture and soil type influence the ability of the weevils to emerge from the soil. Drought can delay adult emergence until rain or irrigation loosens the soil.

Adult weevils feed on nuts and live for several weeks. Once nuts reach the gel stage, they are suitable for egg laying. For this reason, early-maturing varieties are infested first. The female weevil drills a hole through the shell and deposits one or more eggs within the developing kernel. A single female lays eggs in about 30 nuts.

Larvae hatch from the eggs and feed for about 30 days inside the nut, destroying the kernel. Emergence of full-grown larvae from nuts begins in late September and continues as late as December. Larvae burrow 4 to 12 inches into the soil and construct a cell, where they remain for 8 to 10 months. Most of the larvae then pupate and transform to the adult stage within a few weeks. However, the adults remain in the underground cell for an additional (second) year before emerging from the soil the following summer. Those larvae (about 10 percent) that did not pupate after the first year remain as larvae for 2 years and then emerge from the soil as adults the third year.

Control: Foliar insecticides are currently the most effective treatment for pecan weevil. Once nuts reach the gel stage, insecticide should be applied if adult weevils are present. It may be necessary to continue spraying at 7- to 10-day intervals until shuck split, as long as monitoring shows weevils are emerging in significant numbers.

Certain trees have greater weevil infestations than others. These "scout" trees can be used to monitor the presence of adult weevils. Refer to Extension publication L-1808, "Sampling for Adult Pecan Weevils in Texas," available from your county Extension office. One monitoring method involves jarring limbs to knock adult weevils onto a sheet placed on the ground. Wire cone traps also can be placed beneath trees to capture adult weevils as they emerge from the soil. The number of captured weevils can be recorded periodically. Trap information can help you decide when and how long to continue insecticide sprays in relation to crop maturity. Information on the construction and operation of wire cone traps is available from your county Extension agent or Extension entomologist.

Pecan weevil infestations spread slowly unless aided by man. Infested nuts can be the source of a new infestation and should not be transported to uninfested orchards. Also, infested nuts should be destroyed after harvest.

Early harvest, before weevil grubs have exited from the nuts, also aids in control. Since grubs are physically removed from the orchard by early harvest, this practice can reduce weevil infestations if done each year.

There sre several insecticides that will work but I would ask the extension Service for the best one for your set up and yard.

Here is a web site with additional information on raising pecans and their contact page you can select the county you reside in.
http://aggie-horticulture.tamu.edu/extension/homefruit/pecan/pecan.html

http://county-tx.tamu.edu/