March 21, 2016

Spring Dormant Spray Time!

It's just about time to begin thinking about a dormant oil and copper spray for your fruit trees! The apple trees are getting ready to silver tip in the orchard here at Royal Oak Farm Orchard in northern Illinois and that is a sure sign that spring has arrived!! It also indicates that just as soon as the nights stay above freezing, it will be time to do a dormant oil and copper spray. The oil (mineral oil) is sprayed for mites, scale and aphids because spring is the time to cover those eggs at the base of the buds before they begin to hatch.  The oil smothers the eggs and they suffocate before hatching.  Below you can see aphid eggs that were laid last fall.

Aphid Eggs

Copper is also sprayed at this time for control of fire blight and to aid in the suppression of apple scab pathogens, both being severe diseases that can destroy a crop as well as the trees. We also have to be aware of the spring critical temperatures as the buds progress in development. Each spring I post the spring critical temperatures chart from Utah State to help you determine at what stage your fruit trees may be at as spring progresses.

Critical Spring Temperature Apple Pear

Critical Spring Temperatures Stone Fruit

Ever wonder how the fruit trees know when it's time to come out of dormancy? Well, the trees won't come out of dormancy until they have endured a certain amount of time with temperatures between 32 and 45 degrees Fahrenheit. Once the number of chill hours they need is achieved and temperatures warm in the spring, the trees come out of dormancy and resume their normal growth. The number of hours required at cooler temperatures is known as the chill requirement or chill hours. As of this afternoon we had accumulated approx. 751 chill hours from October 1 of last fall. Most apple varieties require 400-1000 chill hours, so most of the trees in our area have met their requirement and will come out of dormancy just as soon as temperatures warm. Growth resumption can be predicted by tracking what we call growth units. Growth units are the number of degree hours above 41 F. For example, if the temperature averages 51 F for and hour, then 10 degree units are accumulated. Bud break initiates after approx 3710 F growth units accumulate, and progresses depending on the temperature. We do our dormant oil and copper spray generally around April 10. The best time to spray is at silver tip....when the buds have that silvery/gray tinted fuzz on them. You can use the chart below to determine the growth stage your trees may be at.

As I mentioned earlier, now is the time to do our fire blight copper spray and our horticultural oil spray.  We want to get the copper on the trees before they reach full 1/4” green and the horticultural oil can be sprayed at the same time in a tank mix or done as a dormant,silver tip,green tip, or 1/4” green spray.  In other words, your oil can be sprayed at any time from silver tip through 1/4” green providing you are using a mineral oil based product such as Superior Oil 70sec or an off the shelf Horticultural Oil such as Bonide’s All Seasons Horticultural Spray Oil.  Your copper spray should be done before the trees reach 1/4” green to avoid any phytotoxicity issues.  For your copper spray you can also use an off the shelf brand such as Bonide Copper Fungicide RTU (Ready to Use).  Both of these products should be available at your local hardware store or garden center of from

A dormant oil and copper spray should not be done until we get at least a 24 hour period that is above freezing at night. The oil cannot freeze on the trees, but it pretty much dries within about 24 hours. Once dry, there is no chance of it freezing.  We usually get at least one 24 hour period above freezing at night before the trees get to 1/4" green. 

This “window of opportunity” for dormant sprays for fruit trees depends on the bud stage of your target fruit tree. You can follow these guidelines:

Apples: swollen bud to 1/4” green
Pears: swollen bud to cluster bud
Peaches/Nectarines: swollen bud to pre-bloom
Apricot: before bloom

When applying, spray trees just until they are dripping to get good application on all the stems and crevices at the buds. If you are using horticultural oil alone, use a rate of 2% (mixed in water) for best results or follow your chosen product’s label rate.  For situations where aphids have been real problems in the past, consider adding an insecticide (such as acetamiprid, etc.) to 1.5 - 2% oil or use one of the Bonide RTU (ready to use) pre-mixes for insect pests.

March 9, 2016

Time to Prune the Home Orchard

Even though it’s not March 21 yet……spring is upon us!  In our area, northern Illinois, our apple trees are beginning silver tip and it’s time to begin planning our spray protocol for coming spring season.  Our pruning began back in December and we are just finishing up. You may not have 16,000+ trees like we do here at , so many of you may not have pruned your trees yet, but now is the time to prune if you have not done so already!

When to Prune

For the home grower that has 2 or more fruit trees, the better time to prune in our region is probably mid to late March when the daytime temperatures are  a bit more bearable.  The earlier in winter you begin to prune, the more likely you may open the tree up for freezing in severe temperatures if those temperatures arrive too early in the winter.  So the best time to prune is late winter or early spring, before the buds open up for the new growing season. 

If you have just planted your tree(s) this past growing season, you may not even need to prune your trees at all through this first year.  You can then begin training your tree(s) this next May and June and do any minimal pruning at that time.

How to Prune
It is very important to know the difference between training your new apple trees and pruning them.  Training begins when the tree is planted and continues throughout the life of the tree. 
Training is primarily used for proper positioning of the main scaffolds of the tree.  A properly trained tree can save many hours of  very difficult corrective pruning later!
Pruning, on the other hand, is used to thin the branches of your tree to allow more light into the tree canopy (the area covered by vegetative growth).  When all the leaves of a tree are exposed to more light, the tree produces higher quality fruit.

For more on training and pruning your young fruit trees, download T. R. Roper’s article  .

Rather than post the various yearly stages of pruning trees, let me refer you to an excellent article on that will cover the first four years of pruning a young tree, whether it be apple trees or stone fruit such as peaches.
I hope you find these articles useful!  As always, if you have any questions contact me anytime via comments or through our !

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