Key takeaways
- The “I” stands for Integrated — biocontrol is one tool. Pesticides, physical methods, plant health and trap-crops all sit in the same kit.
- Choose biorational (soft) pesticides; target spot-treatments. The era of broad-spectrum, broad-coverage sprays is ending.
- Compatibility is complex. Check inert ingredients (oils, surfactants) as carefully as the active ingredient — the inerts are often more harmful to beneficials.
- Physical controls — handpicking, vacuuming, web-wiping — can be wildly effective. Two man-hours per season kept a 50-sq-ft nasturtium plot aphid-free.
- Trap-crops lure pests away from the cash crop; banker-crops give beneficials a place to live inside it.
The I in IPM is for Integrated. Sitting squarely on the narrow shoulders of the good bugs is the single largest responsibility in a well-crafted integrated pest management program — but matters can be taken into your own hands. You can help the good bugs along while hampering the pests. Tweak too much and you re-take the responsibility. Time to learn how.
Biocontrols Defined
“Biocontrol agents,” or biocontrols for short, is industry nomenclature for biological pest control agents. Biological in the sense that these agents are living, multicellular organisms capable of acting on their own accord, given conditions in which they can do so. Pest Control in the sense that these biocontrols, as predetermined by Ma Nature, consume what we, as humans, consider pests. And as we purchase and employ these organisms to work on our behalf, they are Agents.
Biocontrols can be anything by true definition: if you obliterate a mosquito which lights on your arm and begins to suck your blood, you are a biological pest controller — if you consider the mosquito a pest. The same is true of an anteater if the ants are pests, or a chicken eating a grasshopper. In this industry, though, biocontrol agents are very specific to certain species of insects, mites and nematodes. Two categories fall under the industry definition:
- Natural enemies already existing and volunteering on their own at the site needing pest control.
- Commercially produced biocontrols introduced into a site (which, by species, may already exist in limited numbers as natural enemies).
USDA Permits & Why “Beneficial Insects” Isn’t Quite Right
Transportation and introduction of produced biocontrols is regulated by the United States Department of Agriculture (USDA) and the state in which they’ll be used. The producer and distributor must obtain a USDA permit — PPQ Form 526. The permit process ensures agents not suitable for a specific area remain out of it. They don’t have to be indigenous, but they cannot be allowed to become unwanted pests themselves. They cannot, by the rules of nature, become plant pests — but they can displace natural enemies indigenous to the area by eating the native species’ food.
Although these agents are commonly called “beneficial insects,” the USDA prefers not to use that term — for two reasons: they’re not beneficial by every definition (ladybugs are not beneficial to aphids), and not all of them are insects.
Pesticides & Compatibility
The word pesticides is a blanket term for something which kills or mitigates pests — insects, mites, nematodes, fungi, bacteria, weeds, or anything else harming agricultural or horticultural plants. The names break into two parts: target + -cide. Insecticides, miticides or acaricides, nematocides, fungicides, bactericides, herbicides. In this text, pesticides typically means insecticides and mite control products.
In an IPM program, targeting goes further than terminology. First, choose a pesticide as specific as possible to the pest in question — the days of heavy-duty broad-spectrum pesticides and broad coverage are coming to an end. Then choose one offering the least amount of threat to biocontrols, both introduced and naturally occurring: a soft pesticide. Compatibility is complex, and some pesticide manufacturers take it too lightly — probably for marketability.
Don’t Be Fooled by “Natural”
Natural pyrethrins are often touted as environmentally-friendly — derived from a type of chrysanthemum. Sounds almost edible, right? (Remember, some of the world’s most potent poisons are earth-naturally-occurring.) Natural pyrethrins do break down quickly — a week or two — and pose no long-term threats to the environment. However, this same botanical is very broad-spectrum and very harmful to the vast majority of biocontrol agents. It is not, in most cases, biorational. Some synthetic chemicals are actually less harmful.
Rotenone, another botanical, is bad news: very toxic. Neem oil can be harmful — the oil that is. The active ingredient in most neem-based products is azadirachtin (from Azadirachta indica), which is broad-spectrum to many immature pests, yet seems quite compatible with most biocontrol agents. But watch out for the oil.
The active ingredient is not the only thing to consider when choosing a product you’re hoping will be compatible with biocontrols. With biocontrol and IPM one must learn to think around corners.
How Biorationality Is Measured
Available pesticides are biorationally gauged by the effect of direct contact after twenty-four hours — less than 25% mortality is considered compatible. Inert ingredients (oils, stickers, spreaders, emulsifiers) matter too — they’re often more harmful to biocontrols than the active ingredient. Horticultural oil can be used in IPM thanks to its very short residual; it may even be applied directly instead of sprayed.
Targeting extends to how pesticides are used. Spray only what you absolutely have to hit. Turn off horizontal airflow fans to reduce overspray. Use only enough chemical for the micro-task at hand. Think hot-spots; nothing more.
Physical Controls
Sometimes you have to take matters into your own hands — literally. Handpicking pests is one of the most basic and fundamental forms of physical pest control. Some growers think handpicking is beneath them. Understandable when you have a couple acres under cover or fifty acres of field crops.
The Nasturtium Experiment
A few years ago I tested how washed up that thinking was. A 50-square-foot (5×10) nasturtium plot, with a clear history of black aphid infestation. Scouted weekly; found the first aphid colony within a couple of weeks and applied the old thumb-and-forefinger technique. Two more pioneer-aphid encounters squashed the same way. The nasturtiums grew fast and large and finished the season without a recurrence of black aphids.
Scouting time: 0.05 man-hours. Pinching time: 0.09 man-hours. Total time for the whole season — aphid-free crop and continued scouting: two man-hours. Why can’t this be carried out at a larger scale to the benefit of just about any grower? Ball’s in your court.
Physical Pest Control Techniques
- Handpicking — the thumb-and-forefinger basics, scaled by routine scouting.
- Vacuuming — suck up whitefly adults during an outbreak (Shop-Vac into the greenhouse).
- Web-wiping — soapy sponge removes spider-mite webs and the females inside.
- Trapping — sticky traps used in numbers, with caveats (yellow stickys catch beneficials too).
- Pest barrier adhesive — sticky goop banded around tree trunks; mires caterpillars and crawling ants.
Vacuuming Whiteflies
Have you ever had a whitefly explosion where pests are so abundant they’re like clouds? Disturb the plants slightly and adults go airborne. Take a vacuum cleaner or Shop-Vac in, disturb the plants, and suck up adults by the hundreds, thousands, maybe millions. Instant eradication, instant gratification. Won’t solve your problem — but for every adult vacuumed, dozens of would-be eggs, larvae and pupae never happen.
Web-Wiping for Spider Mites
Two-spotted spider mites produce fine webbing — especially indoors — that runs from one side of a leaf, over the midrib, to the other. A tent of sorts, inside which female mites, eggs and offspring shelter from sprays and predators. With a soapy sponge, wipe the webbing away where practical (rinse the sponge between leaves to avoid transferring the problem). Then mist the plants — not to remove soap, but to increase microclimate humidity. Mites like hot and dry; predatory mites like the opposite. Introduce predatory mites shortly after.
Sticky Traps, Pest Barriers & Cautions
The sticky trap is the scout’s tool, and yes — using a hundred of them traps a hundred-fold pests. Caution: yellow sticky traps are dangerously non-selective and may trap many biocontrol agents. Other traps, like the Japanese beetle trap, can lure mating pairs in but don’t capture them all — making the problem worse. I heartily recommend against using that trap.
Pest barrier adhesive — goop applied in a band around the trunk of a host tree — mires caterpillars, ants and other crawling pests trying to cross it. Time it to the target pest’s life cycle. Spot-check regularly: if the goop becomes bridged with dead pests, the remaining ones walk across the bodies of their dead brethren. Clean it or reapply as needed. Diatomaceous earth and other physical barriers are worth mentioning here too — finer points later.
Part 2 of 2 · click to continuePlant Health, Trap-Crops & the rest of the integrated kit
Plant Health — The Pest Magnet You Can Avoid
Some plants are more susceptible to pests than others. Proximity — to vents, fans, sources of pests — matters. Pests also attract pests: they send out allelochemic substances, chemical signals to fellow-kind that spell f-o-o-d — like a neon sign that says Eat at Joe’s.
Another factor that singles out a plant amongst its identical neighbors is health. Like lions to the antelope on the Serengeti, many pests will target the young, weak plant unable to defend itself — the one that strays because it can’t keep pace. Stunted growth, poor color, maybe a root problem. The health (or lack thereof) is typically detected by pests long before we become aware of it.
One theory: resonance. Every living thing emits a kind of vibration. Healthy plants in the greenhouse all resonate on the same frequency — to pests, nothing stands out as small enough to single out and take down. (Rarely will the lion enter the herd to take them all.) But pests have an uncanny ability to detect the weak plant — the one vibrating differently. The sore thumb.
If your plants are healthy, the crop looks like one big indestructible entity moving in unison like a herd of antelope or school of bait fish. Is plant health important to pest control? It is. Yes, Virginia, plants do have an immune system.
So what’s the difference between an aphid and a lion? The number of fangs. And what’s the difference between a crop of plants and a herd of antelope? The plants can’t run like hell.
Trap- & Banker-Crops
Another way the antelope can keep from being eaten by lions is to hang out with pork chops. Silly analogy, but it holds water in pest control. Another way plants can avoid being attacked by pests is to hang out with crops those pests prefer.
Trap-Crops — The Bean Experiment
For years our bush beans were attacked by Japanese beetles and Mexican bean beetles. One year I planted leftover seeds in an ill-maintained scrub area twelve feet from the garden, while the new beans went in the garden proper. The stressed beans in the scrub were absolutely inundated with both beetle species. The garden beans were the cleanest we’d ever seen. We even got a small harvest from the scrub plants. No fuss, no muss, not a waste of time.
Eggplant is another great trap-crop — it’s a whitefly magnet. Place one in the midst of your cash crop (say, tomatoes) and wait until the first whiteflies appear. They’ll show on the eggplant before the tomatoes. Inundate the eggplant with whitefly parasitoids — Encarsia formosa or Eretmocerus eremicus. The parasitoids will often take off like wildfire, using the eggplant as a breeding ground.
Banker-Crops — Beneficials Live In the Cash Crop
Where trap-crops lure pests away, banker-crops are intermingled with the cash crop. Example: tomato plants can be a difficult host for predatory mites (even though pest mites do fine on them). Bean plants are a very favorable host for predatory mites. Plant bean plants among the tomato plants — trellis pole beans on the tomato plants if you like. Predatory mites like Phytoseiulus persimilis now have a place, right there in the crop being protected, to prosper.
I’m not going to define all possible crop mixes here. You know plants and can put two and two together. Food for thought; I’m not serving up a seven-course meal.
Education
Covered in detail on the Transition Part 2 page. The tidbits: read up, brush up, talk to those in the know (including your supplier of choice), and get out there and do it. There’s no teacher like experience, but to get some, you have to start. Learning by doing is a lesson well remembered.
One big part of these pages used to be scouting. It’s so important it gets a page, or two, all to itself. Read on.
For over 30 years, Green Methods has been a leader in the production and application of beneficial organisms used in biological pest control and integrated pest management programs.