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标题: 果树保养-农药杀虫Dormant Spraying [打印本页]

作者: hunter 时间: 2014-4-6 10:32
标题: 果树保养-农药杀虫Dormant Spraying
本帖最后由 hunter 于 2014-4-6 10:40 编辑

http://marigoldnurseries.com/2012/02/dormant-spraying/

This is the time of year we need to think about protecting our trees and shrubs from diseases and insects. No one really likes having to spray their plants for insects and diseases, but if there is one and only one spray to apply in a year, it's a dormant spray.

What is dormant spraying? Dormant spraying is the process of spraying your trees and shrubs while they are dormant “resting period” during the winter. A plant “breaks” its dormancy when the buds swell up and the leaves start to emerge. Dormant spraying should not be done when this happens. Dormant spray is typically comprised of two ingredients that can be applied together or separately. One is Horticultural Oil and the other is Lime Sulfur. Horticultural Oil is used to prevent insects. Essentially, the oil smothers overwintering insects and/or their eggs. Lime Sulfur is natural fungicide and it kills dormant fungus spores on the plant. All in all, it tries to get rid of garden problems before they start.

Conditions around spraying your plants with a dormant spray can be a bit more complex and hard to time. The temperature needs to be mild, above 5°C. You would want to apply it earlier on in the day so that it doesn’t freeze in colder temperatures, which can cause the oil to be less effective and need reapplication. A pressure sprayer is recommended for spraying. This allows you to get the solution into every nook and cranny of the plant, and allows for even coverage.

When applying dormant sprays, it’s important to remember that it is a very messy job. Suit up in a complete rain-suit or cover yourself in garbage bags. When applying the spray, it should be to the point the plant is dripping so you will probably get some on you. Sulfur is also a rather smelly substance and the oil makes it stick quite well so make sure you're prepared. It can also be beneficial to spray the ground or flower beds around your plants with any leftover spray from your tank. This kills those occasional other critters that hide in the soil or on the mulch around your garden.

Typically fruit plants or anything in the rose family should be sprayed. Apples, cherries, roses, plums, pears, and even raspberries are actually members of the rose family and benefit from dormant spraying. Maples and evergreens do not like and sometimes cannot tolerate dormant spraying.

To conclude users should take all safety precautions while using these products. Although they are considered organic we should still treat them just as we would other products that would used to kill insects, and fungus.

When to Use Dormant Sprays

http://www.mcdonnellnursery.com/html/dormant_spraying.html

Dormant sprays need to be applied when the leaves are off the fruit tree. These sprays should be used two to three times during the winter for maximum success. The first spraying should be in the late fall if possible. This fall spraying is like a protective coat for your tree. It inhibits disease spores from being blown by the wind to unaffected trees and plants.

Choose a windless, dry day when rain is not in the immediate forecast.

Since winters in this area are on the mild side, you should spray your fruit trees again around Christmas. Again, select a day when the wind is not blowing and there is no threat of rain in the forecast for at least 24 hrs or more. This midwinter dormant spray application is the least critical, and, therefore, if the weather doesn’t cooperate it can be skipped.

The final, and most important, application of dormant spray and oil should be in the late winter or early spring. In this area, Mid January to February is the perfect time. The key is to apply this spray before your fruit tree has formed buds. The beginning of leaf formation is the ideal time, but if your fruit tree has already formed its flowering buds, it will be too late. Spraying dormant spray when your fruit tree is flowering will kill the bees that are there to pollinate your tree and the result will be little or no fruit.

How to Apply

Be sure to follow the manufacturer’s recommendations when using these products.
Apply this spray under pressure with a pump sprayer, or with a hose-end sprayer, covering the areas two times. Complete coverage is required for effective control of all over-wintering pests.
Keep your spraying to plants which have had infestations during the prior year! You don’t want to kill any beneficial insects that may be on other plants.
Be careful about exposing evergreens to the spray which is strong and can cause damage.
The use of a dormant oil mixture may destroy annual flowers growing under or near plants being treated. Completely cover any tender vegetation BEFORE spraying.
Fungus spores can also over-winter on fallen leaves. This is why it is especially important to rake and dispose of leaves if you know you have a disease problem.

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