What's Wrong With My Fruit Tree and What Can I Do?
Homeowners who grow fruit in their backyards or small orchards find that diseases and insect pests can often ruin some of their crop and in some instances, especially if left unchecked; the pests can even damage the tree itself. The truth is that it is difficult to produce totally non insect-damaged and disease-free fruit. That being said, however, in some years it may be possible to grow acceptable fruit without the use of pesticides, but in most years, you should plan having to use insecticide and fungicide sprays. But this is not a deal breaker by any stretch of the imagination nor should it be cause for unreasonable alarm. We offer a concentrated Disease and Insect Control Fruit Spray that is safe on the environment, is easy and economical to use, and in one spray effectively control both insects and diseases on your fruit trees. We use it here at the Nursery so we know of what we speak.
Many problems with small fruit can be headed off by following a few simple rules. (After all, your great grandparents didn't have our modern day technologies and chemicals and yet they still managed to grow eatable- but probably not grocery store pretty- fruits.) Proper site selection (full sun) to proper pruning (an open center section to allow for proper air circulation and sunlight; the old saying to '...prune your fruits so a bird can fly through their tops without touching a branch...' is actually pretty good information.) Pruning out dead limbs and mummified fruits is also necessary to keep down on diseases. Additionally, proper yearly fertilization is necessary to maintain proper tree growth. The goal of fertilization is to produce adequate tree growth to support a quality fruit crop, not to produce excessive tree growth. Conditions favoring disease development or insect occurrence vary depending on the particular disease or insect. Generally, warm, rainy or damp conditions are very conducive for the development of tree fruit diseases. For best control of diseases, fungicides and bactericides should be applied before rainfall to enable a longer contact before being washed off.
There are specific times of the year when certain pests can most easily be controlled. Also during the growing season, at certain stages of tree growth, fruit are more susceptible to particular diseases and insects and damage is likely to be greater than during other times of the growing season.
Scale insects are often a serious pest of fruit trees. Use of a dormant oil (available from our Nursery) just before green tissue appears is most effective against scale insects. Oil also helps in the control of mites and aphids. On peaches and nectarines, the application of a liquid Lime Sulfur fungicide (available from our Nursery) before the buds swell in late winter prevents leaf curl disease.
Apples
During the early part of the growing season, apple scab, powdery mildew and fire blight are the principle disease problems. Apple Scab affects both the fruit and foliage and infections can result in defoliation and malformed fruit. Powdery Mildew primarily affects the foliage and is characterized by white fungal growth on the surface of affected leaves. Fire Blight, a bacterial disease, can be particularly destructive during the bloom period causing blossom blight and shoot and branch die back as the bacteria grow from the blossoms into the shoots. In the Piedmont and Coastal Plain, Cedar Apple Rust can be destructive on susceptible cultivars when they are grown in close proximity to the Eastern red cedar (the alternate host of the fungus on which Cedar Galls develop). Infections are characterized by yellow spots on the leaves and fruit. During the summer period, Bitter Rot, Black Rot and White Rot, can all be destructive, particularly in poorly pruned trees with dead wood within them. The most common diseases during the summer period are Sooty Blotch and Flyspeck. The pathogens which cause these diseases grow on the cuticle of the fruit, but do not cause any damage to the fruit themselves.
Apply the combination spray when the first green tissue is visible and repeat at 7-day intervals until blossoms begin to open. Overall disease control will generally be better if Captan is used. DO NOT apply the combination spray during bloom because the insecticides can kill bees and other pollinating insects. When flower petals begin to drop, make another application of the combination spray and repeat at 2 to 3 week intervals until 3 weeks before harvest. Use a 2-week interval if weather conditions are wet or there have been disease or insect problems in past years. We recommend and sell TIGER BRAND as a combination Insecticide and Fungicide that is easy and safe to use, and is made about 2 hours from our Nursery.
Pears
Pears are affected with many of the same diseases as apples with the exception of pear scab, which has not been reported in North Carolina, and cedar apple rust, which does not occur on pear. Fire blight tends to be more severe on pear than apple and can kill large limbs and even entire trees of susceptible cultivars. Pear leaf spot (fabraea leaf spot) can be important on some cultivars.
Streptomycin, available from our Nursery, is effective on Leaf Spot.
Peaches and Nectarines
The most common diseases encountered on peaches and nectarines are leaf curl, peach scab, and brown rot of fruit (the same fungus also causes blossom blight). Leaf curl can be controlled with a single application of liquid Lime Sulfur mixture, available from our Nursery. The spray for leaf curl must be applied during the dormant season before buds swell.
GUMMING: Every year, we get calls from customers about gumming or sap exudate along the trunks, limbs or the branches of many fruit trees. Sometimes gum indicates the presence of a disease organism but more often than not it results from physiological or environmental conditions. So how you tell? Well, if the gumming is actually from a disease such as bacterial canker or "gummosis", the exudate will be discolored or dark in color. Sometimes there will be fermentation and a foul odor. But if the gumming is due to physiological or environmental conditions, the sap will be clear in color- actually a straw to yellow or light gold in color. Stress from temperatures changes to moisture gradients may also cause gumming. So when you see gumming, the first thing to do is to check the internal color of the gum or exudate. If clear, you are probably OK. But as a double check, you can also cut a small sliver of bark directly below the gum site; if the newly cut internal bark tissue is brown instead of the normal light green, light yellow or even white as found in healthy tissue, you might need to treat for a disease like Phytophthora. Trees with gumming but no evidence of a disease will leaf out and grow on normally.
Use two dormant oil sprays at 2-week intervals before green tissue is present to control white peach scale. When flower petals begin to drop, apply the combination spray and repeat at 2 to 3-week intervals until 3 weeks before anticipated harvest. The two sprays beginning at petal-fall are critical and provide good control of the insects plum curculio and Oriental fruit moth and the fungal disease peach scab. Most insecticides should not be used within the 2 to 3 week period before harvest (check product label for specific instructions).
Cherries and Plums
The fungal disease, black knot, can occur on branches of cherries and especially plums. This is most common when these fruit trees are grown near wooded areas that contain wild cherry. Pruning out these knots as soon as observed and spraying a fungicide available from our Nursery starting early bloom with 2 to 3 additional sprays 7 to 10 days apart can aid in reducing black knot. The disease most commonly encountered on cherries and plums is brown rot. Apply the first combination spray when the flower petals begin to drop and repeat at 2 to 3-week intervals until 3 weeks before anticipated harvest rot.
Additional Tips
- Use personal protective equipment such as clothing, gloves, and a respirator as recommended on the product label.
- Mix fresh spray for each application. Do not save spray mixture for the next application. This is not only unsafe, but the pesticide loses its activity and can also damage the sprayer. Don't mix more than you can use for that one spray application. A GOOD RULE IS TO NOT SPRAY an insecticide during fruit blooms because it is likely to kill pollinating insects such as honeybees.
- Spray carefully and thoroughly to cover all parts of flowers, leaves, and fruit until a noticeable amount of water begins to drip from the foliage. Shake the sprayer often while spraying so that the chemicals do not settle out.
- In most cases for disease control, apply the pesticide prior to rainfall; however, sprays should not be applied closer than 2-3 hours before rainfall to allow for sufficient drying.
- Pesticides should be stored in a safe location that is cool and dry. Liquids should not be stored where the temperature will drop below 32 degrees F.
- Read and observe the instructions on the container label for the time interval between the last pesticide application and reentry into orchard or harvest, if appropriate. (Fruit Sprays purchased from Rabbit Ridge Nursery are as safe and environmentally friendly as possible. Reentry to sprayed areas that were used with our chemicals are limited to the time it takes the chemical to dry.)
Information in this section obtained primarily from publications by The North Carolina Cooperative Extension Service.
We recommend and endorse a North Carolina made Fruit Tree Spray manufactured by Cape Fear chemicals and sold under the trade name of Tiger Brand. As a concentrate, it controls both insects and diseases on Fruit Trees, is fairly easy on the environment, and very cost effective for home owner use. (As with all Chemicals, please read and carefully follow the label directions for mixing rates, or contact the Nursery for help.).