Pecan Weevil
Pecan weevils are a major pest for both commercial pecan production and backyard pecan producers in Comanche and surrounding counties.
Under normal conditions we would expect to see pecan weevils starting to emerge in August. Under normal soil conditions we could expect to see 80% of adult weevils emerge between August 20 and September 10. We have had good rainfall most of the summer but are getting dry now. I am not sure how that will affect emergence in Comanche County. However, some areas of the state are starting to see emergence about 2 weeks earlier than normal. Typically, adult weevils will not lay eggs in pecan nuts until the kernel reaches the gel stage. However, adults can feed on nuts before that point, which may lead to nut drop.
The adult pecan weevil is a brownish weevil about 3/8 inch long. The female’s snout is as long as its body; the male’s snout is somewhat shorter.
The larvae are creamcolored grubs with reddish heads. When fully grown, larvae reach a length of 3/5 inch.
Their presence can be determined by finding legless grubs in pecans during September and October, or nuts at harvest with one (rarely two) small round hole(s) in the shell. Infested pecans can be detected by finding larvae where pecans are being stored or on cleaning tables.
Traps are often used to determine if adults are in the orchard and are the best method to monitor their emergence.
Adult weevils damage pecans by feeding and/or laying eggs in nuts. Damage can occur from the time that weevils emerge from the ground until shuck split but the goal should be to prevent egg lay from taking place.
At least two spray applications, and maybe more, will be required to control the weevil. Typically, the first spray will be August 20 or 22nd, which usually coincides with when the earliest maturing nuts of the early varieties are in the gel stage at the distal end of the nut.
A second application will be needed 10 days later. Again, the date is variable every year, weather and nut variety are two main factors. Again, trapping is the best method to determine control dates and necessity. Commercial pecan orchards that have a history of pecan weevil must be treated to control the weevil.
If you are a homeowner, you will have to decide if you want to try and control the weevil or have a percentage of your crop damaged from weevils.
For homeowners or small orchard owners with a history of pecan weevil, you can help control the weevil by spraying Carbaryl commonly known as Sevin on the pecan trunk. Start late August early September and spray trunks every 7 to 10 days covering a band 2 feet or more all the way around the trunk. Follow label directions.