my walnut harvesting

I've been asked a couple of times in the last two days, so here's what I do when I harvest my nuts, which are fairly heavily affected by the walnut husk fly. The fly lays its eggs on the husks of the developing walnuts in late spring, and the larvae eat and grow in the husk. This turns the husks black, and the black stain can stain the shell of the walnut inside it, and if it's there for too long, can go through the shell and affect the appearance and taste of the nut meat inside. It does not affect the taste in a way that you will enjoy, unless you have decidedly odd tastes.

I pick up the nuts from the ground - usually having shaken the tree as much as I can to dislodge nuts that are nearly ready to fall - every day or two. In all but small trees, it helps to climb the tree and shake it from near the top.

I remove the husks soon after gathering the nuts. It helps to have a not-too-sharp knife handy. Some of them are green, some are fully black and slimy, and some are between these states. Not infrequently the husk is knocked off the nut when it hits the ground.

You might think that it would be the black and gooey husks that stain your hands black. They might, but the green ones do, for sure. They are a very good dye for natural fabrics and fibres, including human skin. It wears off eventually, but if you want to maintain clean hands, wear impermeable gloves when handling walnut husks.

After they are husked, I put the nuts, both black and fresh tan coloured and everything between, into a bucket, put some water on them - not too much, not too little - and vigorously stir them about, changing directions and speeds, to cause them to rub up against each other as much as possible. Pour the water off, and do it again, four or six times, until you get more or less clear water draining off them.

Spread them out on a screen or net to dry. A level surface will work, but you will have to stir or turn them to dry them effectively, and it will take longer. Wind and sunshine help dry them and the sunshine also also helps to enhance the colour of the shell, bleaching out some of the stain.

At this point, or when I'm husking them, I discard any nuts that are damaged or look inferior. It doesn't hurt, if you have the space, to keep them. You can crack them later to see if they are okay. Eventually you'll learn more or less what makes a good or okay-enough-to-eat nut and meat, and what isn't worth dealing with.

To drown the larvae that are still in the husks, I put the husks in a bucket and cover them with water for a day or two, then discard the soggy husks as far away from the walnut trees as I can. I try to collect husks from under the trees, especially those that look like they might contain larvae. 

Jodi spreads the husks out on a tray and tells me that the wasps gobble up every larva.

The larvae, when they are fully developed, burrow into the soil  and overwinter, so they can emerge next late spring as flies, mate and look for walnut husks in which to lay many eggs, to start the process over again.

Last year I had very few nuts, and this year I have lots of nuts and fewer blackened husks. I'm hoping that some predator has learned to hunt the flies, or possibly to burrow for the larvae. It might be that there are fewer flies this year because of a shortage of walnut husks last year. We'll get some hints about this next year.

There is a pesticide that is licensed against walnut husk fly. It has to be applied to the tops of the tree, along with a sweet attractant, by a licensed pesticide applicator. I'm not sure if it's easier to find a licensed applicator (who can legally buy the pesticide) or a 60 foot long applicator wand to reach to tops of larger trees.

I've learned, so far, to live with the pest. I'd love to hear how others are coping, and what is working for you.


Alternate washing method

We had a fairly heavy infestation a few years back, but only the occasional blackened husk since, so yes, something seems to be keeping their population in check around here as well. We cleaned our nuts by putting them in oyster trays (those black basket-like trays that wash up on the beaches around here fairly regularly) and blasting them with an electric pressure washer, which worked pretty well. We have accumulated quite a few trays over the years and would be happy to pass some on if somebody else wants to give that method a try.

Post new comment

The content of this field is kept private and will not be shown publicly.
This question tests whether you are a human visitor, to prevent spam submissions.
The answer can easily be found on this site if you don't know it.
Don't stress - if you get it wrong, you'll get another chance, just try again :-)
7 + 7 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
To prevent automated spam submissions leave this field empty.