by Gary Mount
There’s been a lot of IPM going around lately. At Terhune Orchards, we got it over 15 years ago and we still have it.Quite a few of my farmer friends in New Jersey have it and not just fruit growers, but vegetable farmers too. When I went to a Michigan fruit grower meeting this winter, I found it all over the place out there too! And last winter when Pam and I went to Australia and New Zeeland, guess what? It had spread all over down under as well.
Just what is IPM?It is NOT some terrible agriculturally related calamity NOR is it a new esoteric illness only inflicting farmers. IPM is Integrated Pest Management and it’s the best. IPM is a systematic approach to dealing with pests and diseases that damage crops. IPM scientifically evaluates all methods of control and all factors involved in each and then applies the ones that make the most sense overall. Not necessarily the cheapest-although cost is a factor, not necessarily the most lethal to the pest-although effectiveness is a factor, and not necessarily the easiest to use-although safety is a huge factor. A farmer using IPM evaluates these three factors-cost, effectiveness and safety in addition to many others in order to determine how and to what degree, to combat a pest that damages crops.
This seems logical, right? Just use the scientific method and come out with a rational answer. Well, it hasn’t always been that way.
Imagine years and years ago, when everyone lived on a farm. Many different crops were grown and pest damage was accepted as part of growing a crop. Damaged farm crops could always be salvaged in some way-animal food for example. If you grew it for your own use, you could deal with the problem. What came next however was farmers selling their crops to other people. Oops! Damage to a salable item was much more important and not acceptable. And the specialization in growing crops led to increased damage because of concentration of pests and diseases.
When chemical products to control pest became widely used in the 1940’s, they were the magic bullet-one solution fit every problem-don’t need to think about anything else. Harmful effects of long persistence of the chemical and/or possible harm to other species weren’t well understood and not a concern to most people.
But what about today and IPM at Terhune Orchards? IPM is accepted as one of the most bio-rational methods a farmer can use to control crop damaging pests and diseases. At Terhune Orchards, IPM has led us into doing some pretty interesting stuff. An IPM scout from Rutgers Cooperative Extension visits our farm three or four times a week to help us determine the presence and severity of pests and disease. The scout counts the numbers of several different damaging insects that are caught in traps on the farm each week. (We are not trying to trap all the insects-just to find out when they are present and when is the best time to control them.)
Maybe you’ve heard of the “worm in the apple”. That usually is the larva of the codling moth. If you are a fruit grower trying to sell apples, you just can’t have any worms in the apples. Years ago, growers had to apply up to 5 sprays to be sure they killed the hatching codling moth larvae. At Terhune Orchards (and most other IPM farms), we add the average daily temperatures, known as degree-days, from when our IPM scout first catches a codling moth and then determine when the first damaging larvae will hatch. We then know just when to spray. One spray does it-that’s one fifth, .20, 20%–that’s part of IPM.
We use another neat technique to control apple scab-a devastating disease affecting both the apple tree and the fruit. We keep a mini weather station (it is how we count the degree days in the codling moth example) and we track the rainfall, leaf wetness and temperature during the apple season. We correlate the length of time the leaves are wet at a given temperature with the occurrence of the disease, apple scab. If the disease is going to happen, we spray. If it is too cold for the scab to develop, or the leaves aren’t wet long enough, we don’t spray. We substitute information in place of chemicals; without that information, we would have to spray on a calendar schedule to be sure of having no scab. Many years we save over half the scab sprays-that’s .50, 50%–it’s part of IPM.
I could write on forever with examples of IPM, but the last story to tell is the best. It’s a technique we use to almost completely eliminate insect sprays in peaches. The two main insects that attack peaches are the Oriental Fruit Moth (OFM–the worm in the peach) and the Peach Tree Borer (PTB-a wood boring insect that gets inside the bark of the tree.) The system is based on the fact that the male moth finds the female by following her scent through the air. We purchase tiny plastic tubes that look like the twist-ems which close off the end of plastic bags. They contain the synthetic scent of the female OFM and female PTB. This scent is actually the same attractant our IPM scouts use to attract male moths to their traps. The difference is that we attach one twist-em to each tree in the whole peach orchard. I can’t help but think that this much female scent out there must attract every male OFM and PTB in the county to our orchard!! But, and it’s a big but, when they get here, there is so much scent around that they become confused and cannot find the real female OFM or PTB. I shouldn’t have to explain further-after all, you have read this far-but if the males cannot find the females, there is no mating, no egg laying, no hatching of worms or borers and best of all, no need to spray. That’s great and it’s part of IPM.
So that’s three ways we use IPM at Terhune Orchards. If you are visiting sometime and would like me to show you more, just ask.