Posted on Aug 16, 2019 | by Kerry Kelley
Gardening certainly has evolved in recent years. Once upon a time, who cared about needing an arsenal of plant pharmaceuticals and fertilizers in the shed, how much water we used to keep those beds full of annuals pretty, or where our seeds or tomato plants came from?
These days, it's not so easy. Before we indulge our planting passion, there are many ethical dilemmas we must overcome, regarding the use of chemicals, fertilizers, and even which plants we choose. A few state and local governments have made some of those choices for us, but there are still questions that seem to have different answers, depending on who's answering.
Over the course of this series, we'll look at some of issues we're wrestling with, and what we can choose to do.
Pesticides are products most of us would rather not use unless truly needed. But when is that? To make that determination, first the problem must be correctly diagnosed. Is it an insect, disease, or a cultural problem? Many plants can tolerate some level of insect feeding or disease without a great deal of damage. Sometimes simply hosing a plant off or removing diseased foliage may be enough to keep the problem at bay. If treatment does become necessary, READ THE LABEL! Some insecticides don't work on specific insects or fungi, and some products should not be used on certain plants. And none of those products will correct soil pH, nutrient deficiencies, or overwatering, all of which may be mistaken for disease. A properly cultured plant is the best defense--stressed plants are far more likely to be attacked and damaged by pests.
All pesticides have pros and cons. Synthetic chemical formulations are not all bad, just as organics are not all good. In some cases, a synthetic may require just one treatment, while an organic may need to be reapplied several times. But if it's organic, does that matter? It may, since besides the negative effect on our free time and our pocketbooks, some organic insecticides, such as Spinosad, are toxic to pollinators until the spray dries--up to about 3 hours. The more often they are sprayed, the more chance there is of an innocent bystanding beneficial being harmed.
Timing of application is always important--spray in early evening when pollinators are not feeding, and avoid spraying plants in bloom. Spinosad is also slightly to moderately toxic to fish and aquatic invertebrates, moderately toxic to earthworms, and highly toxic to eastern oysters. So, we should never assume that just because something is organic that it is completely non-toxic to other wildlife. Always take care to use products carefully and appropriately, organic or not.
While contact killing products like Spinosad have little residual effect after drying, there are some chemicals that are effective over a long period of time. Termed "systemic," these are taken up into the plant's tissues, and act on the pest as they feed.
There is much current debate over one specific type--the neonicotinoids ("neonics"), as to just how toxic they are to pollinator populations, especially honeybees. Honeybees have been in decline for roughly the last 10 years, scientists citing parasites, viral pathogens, habitat loss, and increased fungicide and pesticide, especially neonic, use as likely causes.
Several types of neonics were restricted in Europe in 2013, and this year the EPA banned 12 (of 59) neonic products which contain one of 2 specific chemicals. There are hundreds more still registered for use to be reviewed by 2022. Neonic coated seed is commonly used in agriculture, especially with corn and soybean crops. The chemical companies have long maintained that their products pose little or no threat to bee populations, using the European ban in their defense, claiming it had no effect other than costing farmers millions of dollars. Others point to lab and field studies of several types of bees, showing that neonics adversely affect their foraging behavior, reproduction, and ability to overwinter. In addition, there are studies suggesting that neonics work their way up the food chain, negatively affecting birds and deer.
Residents of Maryland and Connecticut don't have to worry about taking sides, since legislation has been passed regarding neonic use on plants. As restricted pesticides, only certified pesticide applicators may use these products in these states. In Connecticut, plants may not be sprayed by licensed applicators when in bloom, and in Maryland all retail sales are banned. Although originally in the bill, Maryland stopped short of prohibiting sales of neonic-treated plants, so consumers may still be inadvertently harming bees by purchasing such plants. As systemics, neonics persist much longer in the plants, and have longer term effects than non-systemics.
Many growers are now labeling their neonic-free plants so that concerned gardeners may make informed purchases. Most independent garden centers should know, or be able to find out, whether their vendors are using these products. If this is important to you, ask, and don’t shop where you get an unsatisfactory answer. These products will eventually wear off—current thought is in a year or two.
If you’ve already purchased plants and their neonic status is unknown, you can still take steps to protect desirable species. For pollinator plants, remove the flowers; for larval food sources (like milkweed for monarch caterpillars) cover with VeggieMesh or other plant fabric for a couple of years.
IPM, or Integrated Pest Management, is the backbone of environmentally safe pest control. Instead of gardens full of plants requiring copious water, fertilizer, and frequent chemical applications, IPM strategies start at the beginning with making informed plant choices to prevent problems. Regular scouting identifies pests early before populations build. And when control is needed, the safest methods are considered first, including organics, barriers or traps, and beneficial insects. It’s certainly a far cry from how many of our grandparents gardened, but it’s a sustainable and practical method for today.
Some basic knowledge will help you along the way. The absolute best tip is to search online for your state + "cooperative extension". Almost all states will have a part of their Agriculture Department, usuallyworking with a local university, devoted to information for home gardeners. It's free, it's provided by experts, and it applies to your local area. You''ll usually find numerous fact sheets on everything from growing vegetables and container gardening to lawn maintenance and local wildlife.
Insect Control IPM Tips for the Home Garden
- Know your conditions before you plant. A healthy plant will cope with stress much better than an improperly cultured plant. A stressed plant can easily succumb to insect feeding. Most important: know how many hours of DIRECT sun you have and how well your soil drains, and plant appropriately. Here's a link to a soil perc test you can do at home. Depending on what you're planting, your soil PH may be of importance. Usually, it's to be sure that the soil is acidic enough for ericaceous plants such as rhododendrons, gardenias, blueberries, and camellias, for example. You should be able to purchase a simple test online or at your local nursery. Native species are usually better adapted, but know your garden--planting a native rhododendron in a poorly drained spot spells disaster.
- Know what your plants are susceptible to. For example, Dwarf Alberta Spruce often turn brown from spider mite (but not necessarily a lack of water), aphids love calibrachoa, and caterpillars can destroy a crop of cabbage. Folks often notice black, sooty mold on their hollies, but the real culprit is aphids producing honeydew that the mold grows on. This is where your cooperative extension website will come in handy. Here's one list I found for Texas, but it will apply to most states: Texas Insect Susceptibility List.
- Grow it right. Proper watering, and in some cases fertilizing, is essential to the health of your plants. Weakened plants are more easily damaged by pests.
- Watch the fertilizer. Feeding too much promotes a lot of young, tender, leafy growth, which is what aphids and other insects love. If you're seeing insects, consider cutting back on the nitrogen.
- Scout once a week. Insects usually hide UNDER leaves, so take a close look at a few of the older leaves and some of the fresh, new growth. In addition to actual insects, take note of holes, chewed leaf edges, spots, discoloration, or "dirty" specks under the leaves. Noticing a problem early often allows you to use gentler controls. Always check plants before you buy so you don't bring home a problem!
- Try a water spray. At first sign of pests such as aphids, try spraying the plant with water, hard enough to knock off the pests. Often this will be enough if you do it regularly. To avoid fungal diseases, don't spray late in the day or at night. Some plants can tolerate a certain level of insect feeding, so everything doesn't always need to be treated. Or, beneficial predatory insects may be able to keep it in check.
- When that doesn't do the trick, the next step is a safe spray of insecticidal soap, horticultural oil, or neem oil. These are all contact insecticides, so if you miss any bugs they won't be killed. Spray under the leaves, too. Try not to spray when plants are in bloom, but if you must, avoid spraying the flowers if possible. Don't spray in full sun or in the heat of the day, and make sure the plant is adequately watered first. You may need to repeat this treatment in a week or 10 days--read the label!
- Try the barrier method. For vegetable gardens, use fine mesh plant fabric or netting, like VEGGIE MESH. These products let sunlight and water through, but keep pests out. This is almost the only way to keep away flea beetles, as they tend to feed at night and fly back to the trees during the day, and it's a great way to keep caterpillars from ruining your cabbage, broccoli, and kale crops. This method can be also used to save prized ornamentals in years with bad Japanese beetle or other pest infestations.
I'll be posting some blog updates for you which will include what signs and symptoms to look for, and how to identify those pests. Diagnosing the problem correctly is key!