As we enter August shell hardening is upon us for Pawnee and other varieties are only a few days to weeks behind. This means that for Pawnee we are shifting from nut sizing to kernel filling. As a result there are two things to keep in mind: 1) You should be about done with fungicide sprays on Pawnee; 2) Move up to 100% on irrigation of Pawnee.
For our more traditional cultivars with October maturity dates you need to keep irrigation at about 50% until mid August. This will be enough for sizing if your system has the appropriate capacity. In mid-August you should turn irrigation up to 100%, which is the recommended equivalent of 3600-4000 gallons per acre per day in order to fill the pecans.
You probably need at least one more scab spray on moderately susceptible cultivars like Stuart, Schley, Cape Fear, Kiowa, etc. but you can end scab sprays around mid August on those varieties if they are relatively clean. You will likely need at least 2 more sprays on Desirable but by the latter part of August you can end those as well if they are relatively clean. The exact timing will depend on when exactly Desirable is done sizing. Desirable has a habit of waiting until the last minute to size the nuts and within a preiod of just a few days it will all of a sudden increase dramatically in size. They will be vulnerable to scab until that sizing is complete and the shells harden.
Additionally, if you are considering mechanical fruit thinning, now is the time to do so on most cultivars. It may be nearing the end or even a little late to thin Pawnee at this point, but most other cutivars should be thinned within the next 10-14 days if you are considering this.
You will likely see water stage fruit split begin on many cultivars over the next few weeks. Don’t panic. The trees will drop some nuts. The heavier your crop load is, the more it will appear you are losing but this will only last a few days and it will end without significantly impacting your crop.
Don’t forget about shuckworm sprays in mid August and be on the lookout for aphids (especially black aphids) and mites. They will be arriving this month! August is the month that makes or breaks a pecan season and determines the possibility of a return crop the next year.