Organic Pest Management For The Lawn
Many municipalities are moving to ban the use of herbicides and pesticides, if not completely, at least practically. In Ontario, we have a province-wide ban on the use of pesticides for cosmetic purposes. In addition, for many of us, we are looking for better solutions so that we can resort to the use of chemicals, if not at all, at least less often.I have not had a significant pest problem in my garden overall, I think largely due to good garden cultural practices. Generally these are:
- Plant the right plant for the conditions (sun or shade, soil conditions, moisture conditions etc.).
- Treat the soil well by adding organic matter either in the form of compost or mulching with finely shredded mulch.
- Use good plant maintenance practices: mulch to reduce weeds and retain water, water deeply when needed, prune out dead or diseased areas when spotted, weed and deadhead regularly. All these practices help your plants avoid being under stress in the first place. Stress makes plants more susceptible to pests and disease.
- Resort to chemical use only when the plant health are in jeopardy (and be reasonable in your expectations). If possible use organic controls first (including hand picking bugs) and resort to synthetic controls last.
While I do have grubs in my lawn from that dreaded Japanes Beetle, living on 2.5 acres means resorting to chemical or even organic solutions for grubs is just not cost effective. So I decided to change to an organic lawn care program in the hopes of creating a healthier soil and thus healthier lawn, increasing the ability of my turf to withstand any grubs or other pests. To learn more about my fertilizer and cultural management choices please see my information on Moving To Organic Lawn Care.
This article addresses some of the information I researched specifically on weed and pest management. Again I should note I am not a lawn care professional, this is just a summary of what I have spent a lot of time researching and plan to adopt for my own lawn and garden.
Weeds
The best treatment for weeds is deterrence. The best deterrence is a healthy, thick, lawn. Weed seeds need light to germinate so shading and crowding them out helps reduce the number of weeds in the lawn. This means practicing good cultural practices for your lawn.
- Mow as high as your grass will allow, for me that means 2 to 3 inches.
- Mow often. The more you mow, the more lateral growth you will have in your lawn helping it to thicken and crowd out weeds.
- Water deeply and less often to encourage deeper roots.
- Mow weeds off or hand pick, do not let weeds go to seed.
- Over-seed, over-seed, over-seed.
Try horticultural vinegar for weed control. For spot treatment or for small areas of pure weeds, many people have reported success with 20% vinegar sprayed on the foliage. To a gallon of vinegar, mix a tablespoon of liquid dish soap and two tablespoons of molasses as wetting agents. Apply full strength from a hand sprayer. Be careful not to get any spray on you, in your eyes or inhale it since it is an acid. Be aware that vinegar is non-selective, if sprayed on your lawn it will damage the lawn as well. I have heard that heat makes it work better. This means it may be more advisable to spray broadleaf weeds in your lawn in spring. The wider surface are of the broadleaf weeds will get enough vinegar to harm them despite the cooler weather while the narrow grass leaves may get by with less harm where they are in contact with the vinegar.
Some have used corn gluten as a pre-emergent. It reportedly has an enzyme that inhibits the production of root hairs on newly germinated seeds. This means they cannot absorb water as well and as a result do not take hold and will die. Health Canada (through the Pest Management Regulatory Agency) has just recently approved corn gluten as a weed control agent. The downsides? In wet years the seed will likely still survive. Corn gluten does not discriminate among seeds so it affects your ability to over-seed your lawn. It also may build up in the soil thereby affecting your ability to over-seed in future years.
A note on aerating. Many lawn care professionals now recommend that you aerate your lawn annually. While I did aerate my lawn in the first year I switched from chemical to organic I have not done so since. My thoughts are aearating each spring or fall just brings soil and weed seeds to the top of your lawn, exposing them to the sun and thus increasing the chance of weed growth. Aerating and dethatching also stress your lawn, again promoting weed growth opportunities. With an abundance of microbes and earthworms from an organic approach, your lawn should not have thatch (the earthworms will eat it!) and it should be aerated naturally.
Grubs
I have a big problem with Japanese Beetle and their offspring, white grubs. Unfortunately I live in the country so likely any practice I use will only have short term effect. In addition, most organic products are just too costly for such a large property. For me this best approach will likely be to ensure my lawn is the healthiest it can be through the use of organic lawn care fertilizers.
Many have reported success with nematodes, while others have not. From what I have been able to gather, this largely may be due to the quality of the supply of nematodes and application.
Beneficial nematodes are parasites that only attack the white grub. In cold weather areas such as ours they do not over-winter in the soil. They come on a sponge which is wrung out into a bucket of water. The water is then sprayed on the lawn. Success depends upon the number of 'live' nematodes that were actually on the sponge (compared to what was listed on the package) and application. The best time to apply is both spring and fall in our area (May and August) on a rainy day (to ensure they stay wet longer until they can find a host grub). Also apparently if the screen on your sprayer is too fine, it could damage the nematodes and effectively kill them before they reach the soil.