It would seem logical that if you can physically stop the bugs and beasties getting to your crop, then there should be no need at all to use a pesticide. It is such sound logic that over the summer season at Hazeldene, we asked one of our baby leaf growers to have a go and see what happens.

John Rimmer grows his crops in West Lancashire and every summer he battles with aphids, butterflies and flea beetles.

“The flea beetles especially love eating the Mizuna,” says Rimmer. “As soon as we get the first real heat of the summer, it’s party time for the adult flea beetles. They especially like grazing on the cotyledons of the emerging Mizuna. If they have not killed the poor plant at that point, they continue to feed on new leaves, leaving pinprick holes behind.”

The trouble is that the leaves then grow and the pinpricks become big holes in the leaf. This is not very customer-friendly and so, after a particularly severe flea beetle attack, Rimmer has no other option than to turn the crop back in.

Traditionally, baby leaf growers would have applied a pesticide, sometimes quite frequently during bad attacks, but there seems now to be a real chance that we could have a workable alternative.

For this evaluation, we picked a very robust crop net. More of a mosquito-type net than a standard non-woven fleece, this net can last over many seasons if handled carefully.

The nets are manufactured to meet several weave sizes, depending on the particular pest that we are trying to prevent. Rimmer chose the standard flea beetle net for the trial.

It’s very important that the net is rolled on and properly weighted, pegged or dug in prior to the emergence of the crop. If you miss it by a day, then it’s a home run for the flea beetles.

Whatever happens, we must not be tempted to take it off mid-way through the growing cycle. The flea beetles are just queuing up to charge in there.

So what did we find on the day of the great unveiling? As we took off the net just before harvest, it was clear that there were key differences between the covered and uncovered crops. First of all, the net had done its job and the Mizuna was free of flea beetle damage. As expected, while examining the uncovered section, it was easy to see the flea beetle damage.

So, happy days. No pesticide, no potential residue hassles, no damage and all of it Class I crop. Off down the pub for a swift pint in celebration…

Well, not quite. As with all things, our gains were balanced with losses. The net changes the dynamics of the crop, turning it into a softer product that had been searching for a little more light than it had been afforded.

The result was that we had a more drawn crop, perhaps too soft to handle immediately after uncovering, with a slightly different leaf and stalk dimension. When you cut this more ‘leggy’ crop, the weight ratios per square metre change significantly, resulting in a drop in yield. So what we gained in quality, we lost in yield.

Not that it’s back to the drawing board by any means. We have found a relatively simple method of keeping the bugs off without using pesticides and that in itself is a big win. Now it’s a question of tweaking the method to minimise the yield losses and maintain the robustness of the crop. It’s all about the balance.