Pecan irrigation should be at full capacity

It’s amazing how much water a pecan tree with a heavy crop load can use in late summer. The heavier the crop, the more water required.

Some early pecan varieties have reached shell hardening and others are rapidly approaching. This means that the water use requirements of pecan are about at peak demand and will remain so through kernel filling.

Growers should have their irrigation systems running at full capacity at least for most mid-season varieties like Stuart, Desirable, Schley, etc.  This means 3,600-4,000 gallons per acre per day. Solid-set sprinkler irrigated orchards should be applying 1.5″-2″ per acre week, depending on soil type (the sandier the soil, the more water). Ideally, systems should be designed to meet these water requirements within 12 hours.

It’s amazing how much water a pecan tree with a heavy crop load can use at this time. The heavier the crop, the more water required. Sure, you can still make some nuts and have a decent harvest with less water but this will maximize percent kernel, which is required for good pecan prices.

If the trees don’t have a crop, you won’t have to water this much because it is the kernel-filling process that creates the enormous demand for water. Adequate irrigation at this time will also relieve undue stress on the trees, which helps them to return a better crop the following year.

Black aphid trigger

I’ve discussed the need for vigilance when managing black aphid susceptible varieties like Schley, Sumner, Gloria Grande, and Oconee. You have to pull the trigger on this pest before it builds to easily noticeable levels and the population gets out of hand as it did in the photos below. This can happen very rapidly if growers do not pay close attention to populations this time of year.

Mites are a little tougher to know when to pull the trigger on. They can be found in the orchard throughout much of the year and normally don’t reach population levels that do harm. The trees can tolerate them to a point. But, like certain diseases that lay in wait until the right conditions are found. When it gets hot and dry in late July/August and you see a strong mite population on the leaves, they can explode rapidly just as black aphids do, causing severe scorching and defoliation. This normally occurs following a spray with chlorpyrifos or other broad spectrum insecticides but that’s not always the case. I have seen this in orchards where no broad spectrum insecticides were used. Therefore, growers should be vigilant of mites and watch for signs of early scorching which begins along the midrib of the leaflets.

Portal is a good option but has shown signs of weakening in some orchards where it has been used exclusively for a couple of years for mite control. The same could be said of Acramite. If you have aphids and mites, Nexter at the 6.6 oz rate is a good option. It provides quick knockdown and works well on both pests.

Envidore is a good option for mites, providing excellent residual control but does not provide a quick knockdown so it would need to be used before mite populations reach damaging levels. These miticides are expensive at over $20-over $25 per acre so you want to be sure that there are mites present before spraying. There are many things out there that can scorch leaves and a grower can waste a lot of money spraying scorched leaves rather than mites.

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