Flyspeck Apple Disease – Information About Flyspeck On Apples
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By: Kristi Waterworth
Apple trees make excellent additions to the landscape or home orchard; they require little care and most varieties fruit predictably from year to year. That’s why it’s doubly frustrating when maturing apples develop fungal problems like flyspeck and sooty blotch. Although these diseases don’t necessarily make apples inedible, they can make apples unmarketable. Flyspeck on apples is a common problem, but it’s simple to manage with some cultural modifications.
What is Flyspeck?
Flyspeck is a disease of maturing apples, caused by the fungus Zygophiala jamaicensis (also known as Schizothyrium pomi). Spores germinate when temperatures are between 60 and 83 degrees Fahrenheit (15-28 C.) for about 15 days, and relative humidity exceeds 95 percent. Flyspeck apple disease appears on fruits as a series of tiny black dots, typically in groups of 50 or more.
The fungus responsible for flyspeck overwinters on apple twigs, but may be blown in from wild sources or other fruit trees for a period lasting up to two months around bloom time. Many gardeners implement spray schedules to control this and other fungal diseases, but if flyspeck is your primary apple problem, you can easily manage it without potentially dangerous chemicals.
Once flyspeck is active in your apple tree, it’s too late to treat it, but don’t stress — the apples that are affected are perfectly edible if you peel them first. Long-term management of flyspeck should focus on reducing the humidity inside the apple tree’s canopy and increasing air circulation.
Prune your apple tree yearly to open up the canopy and prevent wetness from building up in this tightly packed center. Remove all but a few main branches and train the tree into a structure with an open center; depending on the age of your tree, you may want to prune it in stages to prevent stress. When small apples begin to appear, remove at least half of these small fruits. Not only will this allow your other fruit to grow considerably larger, it will prevent the fruits from touching and creating small areas of high humidity.
Keep the grass mowed and any brambles or wild, woody plants cut back to remove places where flyspeck apple disease fungus can hide. Although you can’t control plants belonging to your neighbors, by removing these close-in repositories of fungal spores, you can minimize the risk of flyspeck on apples in your orchard.
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What are the little black dots on my apple?
The little pinprick spots on apples, pears, and potatoes are called lenticels (LEN-tih-sells), and they're very important. In an apple disease called lenticel breakdown, a nutrient deficiency causes the apples' spots to darken and turn into brown pits.
Beside above, is sooty blotch safe to eat? The conspic- uous symptoms of sooty blotch and flyspeck diminish the outward appearance of the fruit. However, neither disease will cause a serious rot, and affected fruit can be eaten safely.
Subsequently, question is, how do you get rid of black spots on apples?
Spray the apple tree with lime sulfur if you want to keep your apples organic. According to the National Sustainable Agriculture Information Service, lime sulfur is considered an organic fungicide, and, according to Green Harvest, lime sulfur is effective in the treatment of black spot on apple trees.
Can you eat an apple with Flyspeck?
Sooty blotch and flyspeck live on the surface of the fruit. Damage is mainly cosmetic. The apples are still safe to eat. If control measures fail, sooty blotch and flyspeck can be removed with vigorous rubbing.
1. Apple Scab
Apple Trees Affected: McIntosh, Cortland, and Macoun are susceptible to apple scab. There are many resistant cultivars.
Symptoms: Brown or olive green spots develop on apple tree leaves, which may then curl and fall off. On the apple, dark green spots appear on its surface, later to become darker, flaky, and even cracked. Infected fruit will usually drop, and infections may limit flower formation.
Causes: Spores release from infected apple leaves that have remained on the ground through winter. These spores then infect nearby apple trees. Apple scab can also spread from nearby trees that are already infected. Frequent rains and prolonged leaf wetness enable severe scab infection conditions.
Treatment: Rake up leaves and remove them from the orchard before May. Remove abandoned apple trees within 100 yards of your orchard. The University of Maine Cooperative Extension recommends applying preventive sprays such as captan, sulfur, or other fungicides.
Season: According to the UMaine Cooperative Extension, infections can occur as soon as early May when green tissue emerges from the bud. The disease continues to spread all season with each rainfall.
Risk: Apple scab rarely kills trees. Severe cases may cause complete defoliation by early summer. Repeated infections will weaken the tree, making it susceptible to other diseases.
How to Plant Apples
When to Plant
Plant trees when temperatures are cool. Avoid planting during a hard frost, but otherwise, you can put them in the ground during mid-fall or early winter. You can also plant in spring as soon as the ground can be worked.
Getting it in the Ground
Soak the tree’s roots for a few hours before planting. Dig a hole at least twice as wide as the diameter of your plant’s roots and at least 2 feet deep. The bigger the hole, the happier your tree will be.
Apples require full sun, at least 8 hours per day.
Growing apples successfully requires fertile soil. Do a soil test before planting to be sure that your trees will have what they need. Apples need a pH range between 6.0-7.0.
Amend your soil with peat moss, compost, and bonemeal before putting your tree in the ground to give it a healthy foundation.
Apples need an average of 15 feet between trees, depending on the variety. Dwarf trees are best off with 10 feet between trees, and a standard size tree needs closer to 20 feet.
Without pollinators you won’t get any apples, so plan to put your trees near an area where bees and butterflies visit.
Apple Disease Problems
Fungus problems are all too familiar for apple growers, and they can be challenging to control.
Your best option is to know the early signs of these diseases so that you can address problems before you need to take out the entire tree.
8. Brown spots have appeared on the bottom of the fruit that grow large enough to cover the whole apple (this can happen on the tree or in storage).
This sounds like black rot (Botryosphaeria obtuse), a major apple disease across the United States. The decay starts as dark concentric circles at the bottom of the apple and will eventually spoil the whole fruit.
Tree leaves often show indications of it with bright yellow circles known as frog eye leaf spot, and the disease will eventually spread to limbs where it can kill the whole tree.
The best way to combat black rot is to remove all signs of it immediately. Prune out all infected limbs and leaves, and discard them far away from your trees so the fungus can’t return.
9. Your tree shows decay near the roots and on the bark.
It likely has crown rot, a soil-borne fungus leads to leaf and bark discoloration, as well as slower budding. This fungus favors wet conditions and is almost impossible to eradicate once it gets established.
As crown rot with eventually kill your tree, the best way to avoid it is to plant in in places with good drainage.
10. There are ugly brown circular patches on the apples that create lesions in their flesh.
Apple scab is a fungal disease (venuria inaequalis) that can wreck your crop because it creates lesions for brown rot to enter the fruit.
You might notice it in the early spring as sooty lesions on the underside of the leaves, and it will spread through the rain. Infected leaves may curl up and fall off, and the fruit will have dark, scabby lesions.
As the fungus won’t affect the fruit’s flavor, you can peel off the damaged skin and use as normal.
Prevent a future outbreak by removing infected leaves from the orchard in the fall. It’s also a good idea to plant resistant varieties, including Crimson Crisp, Gold Rush, and Mac-Free.
11. A disfigured trunk with sunken, dead patches. This usually occurs around wounds.
Your tree has apple canker, a fungal disease (neonectria ditissima) that attacks the bark and creates sunken, dead areas. Cankers form in the spring, and they can kill off entire branches.
You’re more likely to deal with canker in heavy wet soils, and it’s best to control it by cutting off branches as soon as you see signs of infection.
12. The apple leaves and branches are covered in a light white powder and are starting to shrivel.
You might recognize these symptoms from squash plants, as your apples likely have powdery mildew (podosphaera leucotricha). Though it won’t kill the tree, it can weaken it over time.
As with most fungi, it overwinters in infected leaves, so keeping the orchard floor clean in the fall will lead to less risk the following spring. You should also ensure that your trees get good airflow and are appropriately spaced to not create wet conditions for fungi to thrive.
Powdery mildew resistant varieties include Liberty and Gold Rush.
13. The fruit has developed dull black sooty blotches and tiny specks over the skin
This is usually a sign of multiple conditions that together form a disease complex known as SBFS—sooty blotch flyspeck.
While it can overwinter on the tree limbs, it’s not likely to cause serious problems or harm the fruit. Maintaining good airflow will reduce its spread, but if you can deal with the spots cosmetically, you’re best off leaving it.
14. Your fruit has depressed, large lesions that look like bruises.
White rot, also called bot rot (Botryosphaeria dothidea) is a fungus that affects apple fruit and wood with small circular spots that eventually turn orange and peel from the tree.
This fungus can cause severe problems to late-season fruit, so you should apply organic fungicides from the spring on if you expect it to be an issue.
Prune out any infected wood and remove leaf litter and mummified fruit from branches in late fall.
15. The tree branches are turning brown, dying back, and forming “shepherd’s crook” shapes.
Your tree has fire blight, a destructive bacterial disease that is challenging to control.
Your best option is prevention (avoid nitrogen fertilizer, maintain good airflow, and avoid pruning during the blossom season) and removing any infected plant material at least twelve inches below the damaged site.
You should also disinfect your pruning tools between cuts with a 10% bleach solution to slow the spread.
16. The apple leaves have lesions and orange-reddish spots, and the tree has large, vibrant-orange growths.
Cedar apple rust (Gymnosporangium clavipes) can cause problems for apple trees. It requires host plants like flowering quince shrubs and cedar trees before it can spread, but it can quickly defoliate your orchard.
Your best strategy is to remove host plants and to plant resistant cultivars like Redfree, William’s Pride, and Freedom whenever possible.
17. Your tree’s leaves have yellow or cream-colored spots in the early spring.
This is a likely sign of the apple mosaic virus, which kills off infected leaves by midsummer and will stunt your harvest. Though most varieties are susceptible, it’s common with Golden Delicious, Granny Smith, and Jonathan varieties.
As there’s no known treatment, you should remove any infected trees from the orchard to prevent spread.
18. The apple fruit is forming black, sunken lesions
This sounds like black pox (Helminthosporium papulosum), a fungus that thrives in wet conditions and the bark of old trees. It’s most common in warmer climates and will destroy infected fruit. Apply fungicides when you see signs of contamination and maintain good airflow throughout the orchard.
19. Your trees have wilting leaves and withered blossoms.
Blossom Wilt (monilinia laxa) is a fungal disease that affects apples, pears, and stone fruits. Both the flowers and nearby leaves dry up and wither, usually before they can be fertilized. Any surviving fruit will turn brown and rot.
Fungicides can prevent the worst of the damage, and you should always remove infected leaves and flowers as you see them.
Growing More “Perfect” Organic Fruit
In the absence of chemical sprays, dusts and synthetically manufactured growth-boosting fertilizers, organic fruit growers have learned to live with a few blemishes. It’s a small price to pay, knowing the fruit they grow is pure and natural. But did you know that you can grow more “perfect” organic fruit? Here are our best tips for the handsomest fruit on the block, without chemical sprays.
(For purposes of this article, we’re only going to focus on how fruit looks when it’s not chemically treated. Mottling and pitting caused by disease and insects is addressed in our Growing Guide, in the “Pests & Disease” section of each “How To Grow …” fruit category.)
Ironically, the fruit that looks the saddest when grown organically is the apple. Pears can suffer in the beauty contest as well. These two types of fruit are usually affected with:
- Sooty blotch and flyspeck
- Irregular shape or small size
The good news is that 1) these issues are strictly cosmetic and do not affect the fruit’s interior and 2) there is much you can do to reduce the incidence of these conditions.
Sooty blotch and flyspeck
These are both fungal diseases that appear as dark brown or black smudges or clusters of tiny, round, metallic-black flecks on the apple or pear skin. They exist only on the surface of the fruit and the skin can be eaten if desired, though it’s not terribly appetizing. Sooty blotch and flyspeck thrive in moderate climates with extended wet stretches in the early fall (as on the East Coast.)
To fight sooty blotch and flyspeck:
- Make sure you’re practicing proper pruning, which increases air circulation, which in turn diminishes the opportunity for fungus diseases to get a foothold.
- Use an organic fungicide when problems first arise.
- Buy disease-resistant varieties. All of Stark Bro’s organic fruit trees are disease-resistant to begin with. Let the gene pool of the tree fight off disease instead of having a constant battle with it. The tree/plant will thrive without intervention and give you fruit worth crowing about.
Small or misshapen fruit
Organically grown fruit is often smaller because it’s not fed a constant diet of growth-spurting synthetic fertilizer. If you’re not careful to continually check your soil health and make sure all of the macro- and micronutrients are in proper balance, your fruit quality and appearance will suffer.
For larger fruit with a more uniform shape:
- Grow native. Native plants automatically adapt better to local conditions and will not experience the stress of say, an apple tree that’s been planted in Georgia. Don’t try to grow what doesn’t belong there the result will almost always be smaller fruit, more bitter fruit and less nutritious fruit.
- For tree fruit, thinning is a must. Leaving too many fruits on a limb will 1) overcrowd the fruit, misshaping much of it and forcing it to remain small 2) increase the likelihood of fruit drop and 3) may cause the limb to break under the weight, especially of heavy-bearing trees.
- Use organic fertilizers to keep your soil stocked with the right ratio of nutrients to adequately feed your organic tree.
Start with an organic fruit tree. When you “grow clean” from the start, the tree will not undergo stress when it’s weaned off an early life of synthetic food and pest/disease control.
Choose untemperamental trees and plants. Small soft fruits (raspberries, currants, blueberries, etc.) are easier to grow than fruit trees, although there are many varieties of fruit trees that are quite easy to manage. Trees and plants that are naturally less fussy are far more likely to produce more uniform, spotless fruit without the aid of chemicals.
Consider location. Always plant fruiting trees and shrubs in the sun, but not in the lawn. Sunlight creates strong producers and uniform fruit. Lawns sap nutrients from edibles and have different water requirements. Planting an apple tree in a lawn invites overwatering and fungus disease, which most certainly disfigures/destroys fruit.
Get fruit off the ground. Keep strawberries in hanging baskets to prevent nibble marks, bird-peck holes and wet-soil contact, all of which can cause bruising, blemishes and mold/fungus. Trellis blackberries and raspberries for the same reasons, and be sure to net them come harvest time to keep the birds from poking holes in your fruit.
Grow small. By choosing a dwarf fruit tree, you can be a better bug and disease monitor, and stop problems before they start.
With just a little pre-planning and diligence on your part, your organic fruit can be beautiful on the inside and outside!