Why are there empty Hazelnut shells?



Why are there empty Hazelnut shells?

Fri Aug 07, 2009 11:49 pm

We have a grove of hazelnut trees growing on our land. They're at least 20 years old. They've been growing on this land since I was a kid. My father used to harvest them, but he's gone now, so I'm left to figure out what's what. Last fall/harvest, I picked them off the ground, as soon as I noticed them falling. I dried them in a dehydrator. When I started to open them up, one by one, I found that every one I opened was empty. I opened at least 30 nuts, and every single one was an empty shell. I've read that hazelnut trees can do this, but I don't know why -- some kind of mold? Or did I do something else wrong? Should I open the shells before drying? What causes empty shells? Will the trees ever produce nuts again? I hope this next harvest will be better.

Just today (August 7), I took a premature nut off the tree and broke it open. I was curious. It certainly has a nut growing there. Is this a good sign? Or will the shells be empty again after the harvest?
Glanecia
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empty hazelnut shells

Sun Aug 09, 2009 4:36 pm

There seem to be at least a couple causes of that, that I found (probably there are more)...

Nut Weevil

A small proportion of our hazelnuts are subject to the attention of a weevil. The nut weevil, like all weevils, is a beetle with a long snout or proboscis which has positively elephantine proportions in the female. She uses it to drill a hole into the young nut as soon as it is set and the shell is still soft. A single egg is laid in the developing kernel, and the hole heals over so there is no sign of infestation. The egg hatches into a grub which feasts on the kernel until the nut falls. The now empty nut has a hole where the young weevil emerged.

Parthenocarpy

This is when a fruit is formed wthout fertilisation by pollen and has no seed. This is fine for grapes but a hazelnut with no nut is just annoying. . . . . The fertilisation process must be done before the leaves unfurl as hazel, in common with most other forest species, is wind-pollinated. Milder winters, and consequent earlier leaf-burst, will reduce the amount of nuts produced the following summer.

http://swepstonecoppice.co.uk/Hazel.aspx
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rainbowgardener
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