My approach to pest control in general, is twofold. First, how can I achieve results through bringing the ecosystem back into balance as best as possible, since the pest infestation is symptomatic of there being an imbalance in nature. Secondly, how can I do this in the simplest, safest way possible, given that doing work commercially requires efficiency?
First, I must address the use of chemicals to achieve goals.
Embracing the fact that pest infestation is a symptom of an ecosystem out of balance, we need to reestablish that balance. Imbalances include things like poor plant health, which may stem from poor soil health, or presence of dead material in the plant. Plants living in the wrong growing conditions will have to struggle more to survive. This leaves them vulnerable to disease, so they need our help or to be removed.
People have been sold the benefits of chemical use for both weed elimination and insect control. Chemicals have limited results (even though there may be instances where chemical use is the only option). Where chemicals are successful, they are in a limited way. Even if there is 100% success, it is temporary. It would be analogous to a person taking a psychotropic drug and getting a promised "high" and then needing more and more of the substance to achieve the same result. Then after investing so much time and money into the drug to solve the problem, the person finds out that the problem has not been solved, but gotten worse. This is closer to the truth.
Case in point with herbicides and weeds:
In the landscaped area, it is natural to have some weeds. Weeds are pioneer plants that will grow in any growing environment. Their role in nature is to pave the way to an established ecosystem phase, i.e., forest via mature grassland. They are annuals, they grow fast and die to produce organic materials for larger vascular plants.
So we have some weeds. If the ground is cultivated and the soil is healthy, the weeds are easy to extract by hand. In areas of high foot traffic and compaction, the weeds are harder to remove and may leave root materials to grow new plants after extraction.
Lets say we use Roundup to quickly and easily get rid of those weeds. The chemical is designed to kill the hardy pioneer plants, so if a wind picks up, that application is going to get on your lawn or your more delicate ornamentals or on your leg through your pants. Anybody have respiratory problems like asthma? The delivered poison is combined with a salt. Since soil is living (organisms which metabolize nutrients for healthy plants live there), the poison will affect that soil. So will the salt that it is combined with (which remains after). Therefore, the weed dies, the soil dies and becomes impotent, and all the things you have diligently planted, which have been exposed to the overspray will die. Alright, we got rid of the weed right? That was our goal? The even more unsightly dead weed is still there and has to be grubbed out. Even though Roundup is supposed to become inert and non-toxic after 24 hours, there are other chemicals that may remain poisonous and be absorbed through the skin when you go to do what you could have done in the first place, without chemical application - wear gloves.
Now, if we look at the definition of a pioneer plant, i.e., weed - it is a plant that will grow in a harsh, transitional environment where no other plants will grow, to pave the way for a healthy, established ecosystem, we find that by taking a short cut to make our lives easier, we have complicated our situation. Since the soil is dead, the only thing that could possibly grow there would be a weed. Not only that, but because weeds produce a high amount of seed material and have a high rate of turnover growth, they genetically adapt to their environment, specifically the applied chemical. They become tougher. Also, since the soil value is depleted, the second, third and fourth generations of weeds will look uglier than the original weeds you could have easily pulled by hand. And those weeds will spread into your surrounding ground covers and then you are faced with getting them out without stepping all over the ground cover...
If we look at the big picture, the American Midwest was practically the breadbasket for the world. It was an area of deep, rich, black soil that could grow anything because glacial advances pushed the soil south out of Canada during the last Ice Ages. My German ancestors immigrated here during the 1860's. I have copies of the letters in German that they sent back to brothers who remained in the Old World, proclaiming the miraculous qualities of this place and its soil. Since the end of WWII, our dependence on chemical fertilizers, pesticides, herbicides and large-scale farming has skyrocketed. The soil is now poorer and the runoff of the chemicals has made the Mississippi River undrinkable and unsafe to swim in. Fish populations have plummeted. In places like Hawaii, chemical runoff from sugar cane and pineapple crops have killed coral reefs. Worldwide, these chemicals seep down through the ground and get into the deep geologic aquafers, from which we get our drinking water through wells. Less than 2% of all of the water on earth is potable or drinkable. The global human population exceeds 6 billion and we are still using chemical fertilizers, herbicides and insecticides that get into the water.
Case in point with insects:
Take the argument above and replace all the words "weed(s)" and "pioneer plant(s)" with insect pests and my point is made without wasting more writing space. I do need to mention that in order to grow produce (fruits and vegetables), one must have pollinators, and lots of them. These are the bees, butterflies and a host of other insects, which go about making sure the product we need to survive actually materializes. The problem with insecticides is they are not species specific. In other words, we spray for the bugs that eat the plants because they are weak and we kill the beneficial pollinators that give us our food. Taken a step further, the birds eat the bugs that have been exposed to the pesticides and become sick and die. What role does pesticide application around the world play in the spread of bird flu viruses? I don't know.
Solutions that have worked for me:
Cultivated soil percolates water better, gives plant roots room to grow and be healthy, and it looks great. It also makes weeding a breeze. I can take this a step further by obtaining shredded plant material and using it as a mulch dressing. It prevents erosion, keeps in water (reducing overall water usage) and it prevents weeds (those few that do grow are easily removed). The long-term benefit is that the material breaks down, providing humus and nutrients to the soil. Depending on your climate, you may need to mulch 1-4 times per year, a time investment that will save you tens of hours of weeding and gallons of water. In many, geographic areas, green waste, from professionals like me and anyone cleaning their yard, is processed, composted and made available for free or a nominal charge for this very purpose. It also looks great.
Regarding insect pests, the reality is we will always have to deal with them, especially in tropical environments where we don't have the benefit of a freeze to keep down insect populations. There may even be instances where chemicals are needed to control damage. But, I enjoy my work a lot more when I am not worrying about exposure to substances that will make me sick, get stored in my body tissues or even kill me.
A highly knowledgable arborist can balance plant health, growth and aesthetic appearance of everything on a property to limit use of chemicals. Pruning stimulates growth. eliminates dead materials that are a pest's unsightly entryway into a plant, and is a form of sculpture.
Between pruning rounds, a hose-end sprayer that has the multiple flow options (jet or shower are best), can be used to spray off all leaf and trunk surfaces. The leaves are clean and lush and the full range of insect pests are managed. You wash off ants, whiteflies, mealybugs, aphids and even scale (the latter two are tended to by ants who love their sweet secretions). You also get rid of their eggs, thereby disrupting the reproductive cycle of the pests. After that, an application of an organic oil by sprayer makes the returning pests stick and die on the leaves. I have tried canola oil mixed with a few capfulls of bleach, but the best treatment is a mixture of Neem oil with water. One application will usually do, however, you may need to spray once a week, as in the tropics. In the mean time, isolated pest infestations can be pruned out. The key is keep your life simple, be diligent and organized.
A liquid soap is also useful for spraying pests in the same manner. Dr. Bronner's has no phosphates and is available at health food stores. The eucalyptus scented one may also work for you to repel pests. There is a symbiotic scenario whereby you end up having several pest populations supporting one another. Ants like the sweet, sticky secretions of aphids, scale, mealybugs and others. Ants will actually tend to them to get more of what they want. The sticky substances, which end up over all surfaces of the plants, grows sooty mold. The sooty mold covering the leaves prevents sun exposure and production of chlorophyll, resulting in loss of leaves. A coating of sprayed soap acts as a surfactant on the leaves, which gives you an upper hand in spraying off the sooty mold with a hose-end sprayer. There have been instances on high-end properties with guests, where I have actually gone in with pail of soapy water and rag and wiped off all of the leaves!
Natural pest control can be brought in to help out. Praying mantises and ladybugs are common beneficial insects. Lizards and geckos also eat insect pests.
Another aspect of pest control often overlooked as such, is fertilization with good organic fertilizers. The chemical ones will leave their salts in the soil, but a good fulvic acid or a good fish emulsion-based fertilizer will do well when sprayed from a mixture with water. Check for specific plant needs. If you are container composting and have access to a good compost tea, use that. There is a general rule of thumb. Plants feed themselves by dropping their dead leaves to compost under their drip lines. If you are able to do plant specific composting, those plants will have all of their nutritive needs met.
You can control insect pest entry into households by pruning away any plant material that touches the building and keeping a vegetation-free zone of a foot and a half around the whole structure. It can be filled with gravel.