Transition to IPM: Part 2

Cleaning Techniques: Where to Start

If it’s possible, segregate or remove the plant material from the areas to be cleaned. A new indoor area — or one that has never seen pesticides or pests — with a dirt or gravel floor should probably be treated in the same way an emptied one would be treated, though not as intensively. We’ll cover the differences between indoor and outdoor areas in detail. Indoors first.

Indoor: The Empty Greenhouse Method

A greenhouse or growth chamber is perhaps the easiest type of area to prep, since the entire space can be treated. Since we’re dealing with the Green Methods, I won’t offer the easy way out — I won’t suggest you bomb the structure with a fumigant or total-release aerosol, though that is an option. If you do go that route, choose something with a short residual period so you can implement biological controls right away, unless downtime is not a concern.

My suggestions for cleanup will be more manual in nature. After all, that’s part of biocontrol and IPM — the hands-on, get-down-in-the-trenches, old-fashioned approach. Hands-on techniques tend to be very thorough.

All this rinsing might bring up the question of toxic runoff. Contain it if you can — which will probably be impossible — and remember that after this, you won’t be adding toxic substances which lead to runoff problems in the first place.

If you close shop every year and don’t overwinter plants, the bake-and-freeze cycle is a strongly recommended annual practice.

Indoor: When the Greenhouse Is Always Operational

If your greenhouse is always in an operational state, clean things up the best you can while working around your plant material. Bomb if you have to, using a product with the shortest residual period possible. Where water, elbow grease, heating and freezing was the ticket in the empty-greenhouse situation, here chemicals and, better yet, time, will be your path.

In any scenario, plan all of this ahead of time. I’ve often heard frustration from growers who got their hearts and minds in the right frame — their desire very strong — only to find on further questioning that they had just cleaned things up using a powerful chemical with a three-month residual period. If it’s possible, start a biocontrol/IPM program at the beginning of a season: new year, new plants, new attitude.

Most of the problems encountered by growers are related to the growers’ excessive tinkering with things. In other words: if it ain’t broke, don’t fix it.

Interiorscapes — A Modified Approach

The indoor recommendations above are best suited to a greenhouse. If you’re an interiorscaper, you’ll have to make some major modifications. You can still clean things the best you can — probably cleaning some of the plant material directly — including pots and planters. You may even opt to switch out some of the potted plants with pest-free ones, which can be cheaper. The removed plants can then go into an area better suited for cleaning and pest control — if one is available.

Soils and planting media may also benefit from a change-over or sterilization. To sterilize media, bake it in an oven for about half an hour at 140–160°F — the warmer and longer, the better.

Fortunately for interiorscapers, cleaning plant material is often an integral part of the plant-care regimen, so chemical residues tend to be less of a problem. Interiorscapers should be less vulnerable to certain problems that commonly affect greenhouse growers — which makes for an easier, less problematic transition.

Outdoor: Rotation & Solarization

In the great outdoors things are a little easier — rain and wind do a lot of the cleaning for you. No more rinse, soap and rinse again; you can skip all that. You may, however, opt to give your soils a break by switching field or garden areas as part of a rotation plan.

Solarization (if rotation isn’t an option)

If rotation isn’t possible due to limited space — or if your soils have serious problems — a summertime solarization break may be necessary. (Best suited to small gardens and raised beds.) Cover the area with good-quality 4-mil clear poly. Cover the edges with mounded soil, rocks or bricks so it doesn’t blow away or let heat escape. Leave it exposed to the sun for about a month. This will kill soil pathogens, insects and weeds — to a depth of about four inches. If pests reside deeper, turn the soil and repeat.

Bear in mind, garden and field plots are fairly natural and don’t necessarily benefit a great deal from sterilization — you’ll also negatively affect beneficial microbes, bacteria and some good insects.

Rotation & Cover Crops (the better path)

Rotation is a far superior method of giving the problem area a well-deserved rest. Plant your primary crops somewhere else for two to three seasons. In the resting area, plant something that will enhance the soil and rebuild it to full strength.

You can let the area lie fallow, but cover crops work harder: buckwheat, rye, oats — and best of all, alfalfa and clover. Those last two are legumes that fix airborne nitrogen and send it below; they can also be perennial. The others need to be replanted annually. Avoid grasses and sod — they give nothing back and deplete the soil’s available nutrients (though they do reduce compaction).

A transition to biocontrol/IPM outdoors is inherently simpler thanks to favorable natural conditions, weather’s positive effects, and the natural occurrence of good bugs. If things are not too far gone outdoors, wait a month and then go directly into your new way of dealing with pests. If you haven’t been using chemicals with long residual periods and don’t have really terrible pest or disease problems, you don’t even have to wait.

Moving Along to Part 3

Now let’s move along to Part 3 of transitioning to IPM →