Green Drinks Talk in Portsmouth NH

Below is a recap of the talk that I gave at Portsmouth Green Drinks.

Portsmouth Green DrinksReducing the amount of pesticide and fertilizer used on our landscapes.

While it is often assumed that farmers are the major source for the overuse of pesticides this is entirely untrue. Homeowners use between 2-6 times the amount of pesticides per acre than farmers. Most farmers have become much more educated on the proper use of chemicals than the average homeowner. Chemicals cost a lot of money and farmers in general operate under very low margins so it has become essential for them to reduce their usage as much as possible.

http://people.oregonstate.edu/~muirp/pesttren.htm

Here is a quick overview of how we can reduce our use of chemicals on the landscape.
Each of the subjects is really a stand-alone subject so I encourage you to do further research.Reduce the manicured lawn size.

  • Lawns consume a huge amount of resources and are more likely to produce fertilizer runoff than other landscape uses.Mowing uses gas and oil unless you use a push mower.
  • Lawns use more fertilizer, weed killer and insecticide than other landscape use. Even organic lawns need to be mowed and use fertilizer.
  • Think about how much of that lawn you really use and how much is using you. Would some of that lawn better serve your landscape if it were converted to other uses like a vegetable garden, flower garden or shrubs and trees?
  • You can reduce the amount of fertilizer by returning grass clippings using a mulching mower.
  • Also researchers are now coming on board with mulching fall leaves back into the lawn using your mulching mower. A practice I have been recommending, and taking grief about for years. This research is now showing that in addition to adding organic matter and fertilizer, chopped leaves can also reduce dandelions in the lawn.
  • Lawns are a huge source of the overuse of pesticides.
  • How many people use a grub control/fertilizer combo every year without knowing if grubs even exist? It takes between 8-12 Japanese beetle grubs per square foot to show any noticeable damage on a cared for lawn. If you don’t have this many then don’t treat. This is a simple test to do with a bulb planter. Simply calculate the area that the planter will remove and convert that number to square feet. Take several plugs out of the lawn and count the number of grubs per square foot. This takes less time then running down to the garden store for unneeded grub killer.
  • Plant breaks on slopes. A sloped area of lawn, paths or even seasonal vegetation is more likely to cause runoff than a flat area. Sloped areas near streams and other water sources and even roads where runoff will enter the sewer system should always have a vegetative break. Choose hardy, preferably native species for these areas.

If you are not totally organic; use integrated pest management (IPM) to control pests.
IPM includes but is not limited to:

  • Monitoring and correctly identifying pests.
  • The use of predators.
  • Cultural/physical control.
  • Proper planting, watering, fertilizing and mulching.
  • Selecting the right plants for the environment.
  • Selecting insect and disease resistant plants and varieties.
  • the use of pesticides.

What is a pest?
Obviously a pest is most often considered an insect. Technically though in this field anything that affects the health an organism is considered a pest, this not only includes insects and disease but also environmental causes of poor health such as sun scold, wind burn, over mulching etc.
Monitoring and Identification.
Far too many treatments are preformed on pests that are either not present, not properly identified, or not at the level that we call a threshold.

A threshold is the number of pests that have to be present to cause unacceptable damage.
There are different threshold levels for different people, situations and crops. The threshold for say a commercial rose grower that has to have a perfect product for sale may be a lot different from what you might consider acceptable in your garden. You can monitor your insect populations and learn. For example if you see a few aphids on a couple of plants, does this mean you have to go out and spray? Not necessarily. First you need to know if the populations are increasing. Check back in a day or two. Are predatory insects around and how many are present? Are you about to go into a spell of hot dry weather? Most Aphid species are done for when the weather gets around 80-90 degrees for a few days. So you have a few aphids, a couple of days later the populations are not really increasing, there are lady bugs, parasitic wasps, and lacewing present. The weather report is for a hot dry period. Spraying here would be a waste of time.

Keep a record of past problems.
Different problems occur under different environmental conditions.

If you have for example a nice perennial bed that is prone to Botrytis, know what conditions favor the development of this disease.

There is no point in treating with a fungicide unless the conditions for development exist.

Use your agricultural extension service.
Of course I don’t expect you to become experts on diseases and insects from a short talk, so make good use your agricultural extension service.

This is the best recourse you have, it is cheap, and they are not in business to sell you anything so their advice is not tainted. I use them all the time, none of us know or remember everything. It would be nice when they help you out to drop a line to the legislators and Governor, as this is a greatly under appreciated service that is constantly under the budget axe.

Timing of applications.
It is poor practice to treat an insect problem without knowing the pest stage and best control timing. Fungi for the most part are only effectively controlled before symptoms appear, hence the record keeping.

A lot of insects can be controlled in their juvenile stages very easily with soft chemicals such as Soap, Oil, or Bacillus thuringiensis. Later these become much harder to control and more toxic chemicals are needed.

Record keeping and dates of hatch can help in timing insect stages but the most reliable method is using degree-days, the next best method is using bloom time (phenology). (This link is from Ohio but phenology and degree days are temperature and not location triggered. Some slight variation might occur due to variations in local insect genetics but I can’t find a local guide that has this much information.)

A simple description of degree days is that it is the accumulated heat during a season. Scientists have calculated the hatch time of numerous insects for specific degree-days, but not for all.
More information about degree days and some degree-day records kept by UNH using volunteer stations can be found at this site.
http://extension.unh.edu/Agric/GDDays/GDDays.htm

Now I hear wheels turning in the members of my audience that are still awake.
But isn’t the use of any pesticide contributing to pollution of our environment? Well maybe not always. Take the example of an invasive species such as the Hemlock Woolly Adelgid. Assume that you have a nice stand of healthy Hemlock in your yard. How many tons of Carbon dioxide (Co2) and other chemicals are these trees filtering from the atmosphere?
http://www.coloradotrees.org/benefits.htm

How many birds and other creatures are they supporting? Are they shading a stream full of fish? Perhaps they are shading your house and reducing the amount of power you use for air conditioning? Now we have to weigh the use of a pesticide to kill this pest against the losses of all these benefits. Just the amount of toxic chemicals filtered by these trees in a year would far outweigh the small amount of pollution caused by chemical pest control.

Pesticide Use.
Pesticides are part of the IPM approach to healthy plants but they are used sparingly, at the right time and on the right target.

This is a huge and extensively complicated subject and once again your local extension service is the place for you to get specific information so am just going to give you a bit of advice if you do need to resort to their use.

As a rule the newer pesticides are much less hazardous than the older pesticides. These pesticides are generally much more specific to the insects that they kill, and break down more quickly in the environment.

How hazardous a chemical is is different from how toxic it is. Hazard is defined as the potential to cause harm to non-target organisms. For example a highly toxic pesticide that is injected into a tree, or breaks down quickly, or does not easily leach or evaporate may be much less hazardous than a pesticide that is low in toxicity, lasts a long time, leaches or evaporates easily.

Choose pesticides that are specific to the insect you need to treat. Broad-spectrum chemicals such as bifenthrin usually end up causing more problems than they solve. Treat only if the problem exists and the timing is right. Try to treat only the affected plants; you don’t have to treat the whole yard for a few Aphids on your Zinnia.

Two common misconceptions are one, that using a pesticide below the recommended rate will cut down the usage. It won’t, cutting the recommended rate is likely to lead to resistance to the product and the increased use of pesticides. And two, that using over the recommended rate will give you better control, it won’t these products have been extensively studied and using more is both wasteful and dangerous. Always read and follow the pesticide label.

Cultural/physical control.
Keeping your landscape healthy also involves cultural or physical pest control.
This can involve many things. When you rake up pine needles in the fall to control White Pine Weevil, put burlap around sensitive plants for the winter, or mulch, these are examples of cultural control of pests.

Plant choice.
Another part of a healthy landscape is the correct plant choice. Sure you love that flowering crab that you see down at the local garden store, but is it good for where you want to plant it. You need to know, is it the right plant for where you want to put it? Are the soil conditions, light and exposure right for the plant?

Pieris is often planted in a sunny exposure, which leads to lace bug troubles where the same plant in partial shade gets almost no lacebug. Is this a disease and insect resistant variety? If not maybe there is a different variety that is almost as nice and is resistant? Is this an alternate insect or disease host to something that is already there?

I see far too many Crab Apples that get treated every year for Cedar Apple Rust because they are planted in Juniper beds. Junipers are the alternate host for this disease. Spruce and Douglass Fir are frequently planted close to each other without regard to the fact that these trees are alternate hosts for Spruce Gall Adelgid. Though this pest can reproduce independently on Spruce, Douglass Fir nearby greatly increases the problem.

If you are looking at a new planting consider using native species, these are less likely to need extra care.

Predators.
Predators play a huge role in keeping your garden pests down. Though some success has been achieved by releasing predatory insects, predator release is a tricky and an often-disappointing adventure. This is not to say that they don’t work, but so many factors are involved in successful releases that you should be aware of the pitfalls and be familiar with the success rate of the particular species. Research is continuing on improving the survival rate of released predators, but it is still a bit of hit or miss at the moment. It is far more advantageous to encourage the predators that are already there and help with their survival.

Keeping something flowering in your yard all season will definitely help encourage predators, and help them survive. Nectar from flowers is used by many predatory insects, either as a juvenile stage food source, or as a sustaining food when prey is scarce. There are many good lists on the web to tell you the best plants, some are weeds, some you may not like. However almost any flowering plant is better than none.

A good clean water source can help encourage beneficials. You must change this frequently or have it flow to avoid mosquitoes.

A good pile of rocks is an excellent way to encourage predators. The Chinese have used this method for centuries. If you search the web for information most sites you find are about how to get rid of spiders and suggest removing rock piles. But I want spiders. Rock piles can also be used to attract toads and snakes depending on how and where they are built. Slugs, snails and weevils are also attracted to rock piles for shade, but overall these benefit predators more and can kill every slug in the neighborhood with beer traps if you need to. If you are worried about spiders going from these piles to your home, build them as far away from the house as you can. I consider giving a little shelter in the house during the winter to anything that eats biting flies, mosquitoes, aphids and other pests all summer long more than a fair trade. I have had roommates that have done a lot less for their shelter.

Don’t use Bug Zappers.
Bug Zappers though fun are awful. Bug zappers are indiscriminate killers and good bugs are just as attracted to them as bad bugs. In fact research has shown that the majority of insects killed by bug zappers are not pests.

Learn to recognize some of the predatory insects. The majority of insects are not plant pests.

These links show some but not all of the many predators in our gardens.
http://umaine.edu/publications/7150e/

These were not included on the above pamphlet.
http://ohioline.osu.edu/hyg-fact/2000/2082.html

Is this a good bug? (just for fun) Type Preying Mantis eats Hummingbird into your browser for a view of this generally good predator being very bad. No point in buying more than one egg mass unless you have a large garden. The first few to hatch usually eat all the rest.

Watering.
Watering too frequently wastes water, encourages shallow roots, and weak, insect and disease vulnerable plants. Water established plants at the most once a week and water until the soil is saturated but before runoff. This includes lawns. I frequently see irrigation lines wrapped around trees and shrubs in landscape beds. The irrigation waters these plants at the same rate as annuals and perennials that need more frequent watering. Established trees and shrubs only need to be watered during long droughts. If at all possible irrigation should be the drip type, sprinklers that hit plant leaves spread and facilitate diseases.

Fertilizing.
Don’t indiscriminately fertilize plants that look in poor health. In many cases especially for trees and shrubs, these plants have other problems and not the lack of fertilizer. Unfortunately too many people fall victim to the fertilizer sales pitch to fix unhealthy looking plants; a waste of time for plants with other problems.

Trees do not as a rule ever need to be fertilized. Do not use nitrogen fertilizer on any newly planted tree or shrub for at least one growing season, two is better. Always soil test to see if fertilization is needed, and what is the correct makeup and rate of application. Use slow release formulations.

Check Your PH.
Plants growing where the PH is out of the proper range for the species do not benefit much from fertilizer and a lot of this gets wasted. It really makes no difference to a plant whether or not the fertilizer is organic or chemical, but organic fertilizers have other benefits. They break down slowly and often supply needed organic matter. In addition these products are made from waste that would otherwise have to be disposed of. Organic fertilizers also help in suppressing some diseases.

Mulching.
Mulch goes on thin and wide 2-3” deep and never touching the trunk. Proper mulching reduces the amount of water and fertilizer needed to keep plants healthy. Incorrect mulching actually increases the need for water, encourages poor root development and harbors insects and diseases.

Planting.
The number one problem with planting is that plants are planted too deep. Planting too deep is without a doubt the number one problem causing the decline of landscape plants that I see every day. The butt swell and the top of the first major roots where they meet the trunk should always be above the soil surface. Back-fill with the same soil that came out of the hole. New research shows that filling the hole with amended soil causes the roots to stay in that small area of good soil. If the soil is really poor then top dress the area with compost, but remember to keep the total fill including the top dressing no higher than the root collar.

Healthy plants need much less care and use fewer resources than stressed plants, so keep your plants healthy.

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