Tree Fruit Care in the Carolina/Georgia Piedmont
Organic vs Conventional
Deciding whether to grow fruit using purely organic materials and methods or follow conventional growing practices is mainly a matter of personal choice. One can also practice methods between the two extremes, borrowing techniques, materials and methods from each. There are several major factors that one should consider before pursuing a management practice, including:
The closer you go to pure organic, the more time you will have to spend, all other things being equal. This is mainly because the insect and disease-killing properties of organic sprays are weaker and their residual period is shorter than modern chemicals. However, with dedication, one can be successful in producing high-quality fruit, even in our very challenging hot and humid climate using organic methods. In different years, I have successfully produced fruit here in the Southeast using conventional, pure organic and hybrid approaches over the 37 years I’ve been growing fruit.
Weed control is also more time-consuming if one takes systemic herbicides like Roundup® and residual preemergent herbicides out of consideration.
Organic fruit is more expensive than conventionally-grown, if one ignores externalities, which I will because quantifying them is not a trivial task. One sees this in the grocery store quite plainly. This is due mainly to the increased labor required for organic production, but also organic materials are costlier per unit active ingredient.
Species and cultivar
If you really want to grow cultivars that are poorly adapted to our climate, like ‘Bartlett’ pears or ‘Pink Lady’ apples, you will have better success with conventional methods. Fireblight is a deadly disease of apples and pears and only liberal use of antibiotic sprays OR selection of resistant cultivars will permit a useful productive tree life. I have grown both of these cultivars in the Southeastern US. The ‘Bartlett’ came as a mislabelled tree and I took a calculated risk on the ‘Pink Lady’ because I liked the flavor of the fruit so much. Both cultivars set fruit, but died spectacularly soon thereafter to fireblight. A better route is to choose resistant cultivars. A breeding program at the Harrow Research Station in Ontario, Canada specifically bred for blight-resistant cultivars that had a similar flavor and aroma profile as ‘Bartlett’ and their results were quite successful, leading to cultivars such as ‘Harrow Delight’ and ‘Harvest Queen’. Other breeding programs, including Dr. Richard Bell’s at USDA in Kerneysville, WV and the now-discontinued programs at the University of Tennessee released high-quality, blight-resistant pear cultivars. Even greater success for high-quality, disease resistance has occurred for apples at Cornell University, a cooperative effort among Purdue, Rutgers and University of Illinois (PRI) and the privately-financed Midwest Apple Improvement Association (MAIA).
I’ll say more about cultivars later in this guide and list details about many modern and heirloom cultivars elsewhere.
Several peer-reviewed studies have shown that organic fruits and vegetables are no more nutritious than conventionally-grown produce. However, one may also want to consider qualities that were not measured, such as antioxidants and uncharacterized secondary compounds (potential positives for organic) and contamination with harmful bacteria and fungi (potential negatives for organic, due to the reduced disease control and potential use of improperly composted manures). Also, the long-term effects of trace amounts of residual man-made chemicals is still poorly understood, which also favors taking an organic approach.
I will always remember the words of my soil science professor in college who said that a nitrate, phosphate or potassium ion is identical whether it came from a chemical plant or the breakdown of some organic material. He was absolutely correct, BUT the speed at which nutrients are released to plants is ALSO very, very important. Drinking 2-3 liters of water per day is recommended, but while doing this over the course of a day from a drinking glass may be quite healthy, attempting to do this from a firehose is not such a good idea. Organic sources tend to be slow-release, whereas chemical sources tend to be rapid release. Of course, one can mimic slow and steady with multiple, light applications of chemical fertilizers and some chemical fertilizers claim to be slow-release, but our heat tends to speed up the release, so buyer beware.
Despite some of the false information one can find on the Internet, there is only one GMO fruit tree cultivar available to the homeowner, the plum cultivar, ‘HoneySweet’, which is the cultivar, ‘BlueByrd’ (non-GMO), engineered to resist plum-pox virus. There are also few GMO apple varieties engineered to resist browning during processing that have recently been planted by a few commercial growers, but these trees are not being sold to individuals, as far as I can find. Whether or not you think that GMO is a bad thing, a good thing or just a tool that could be used either way is practically irrelevant when it comes to growing your own fruit, because existing fruit trees are almost 100% non-GMO.
Species and Cultivar
Especially important if you are attempting some form of permaculture, but key to any successful fruit-growing effort is to choose what you plant wisely. If you want to minimize spraying and maintenance, then persimmons (Asian, American or hybrids), figs, pomegranates, mulberries, pawpaws, rabbiteye blueberries, (some) pie cherries and muscadine grapes are good choices. Significantly higher time and careful cultivar selection will be needed for apples, pears, sweet and Duke cherries, and native plums. Peaches, nectarines and non-native plums require the most care, though you can help yourself a great deal by selecting locally-adapted, very early-ripening cultivars of these fruits. Special considerations of each are listed below:
Persimmons: Asian persimmons tend to overbear. You should thin the young fruit soon after it sets to 1 fruit every 4-6 inches to ensure good fruit size and quality. It will also increase the life of the tree. Also, try to purchase Asian persimmons grafted onto D. lotus or D. kaki rootstocks. A mysterious malady seems to be more prevalent when they are grafted onto D. virginiana stock. American persimmons and Asian/American hybrids are pretty carefree here. You might have to dust/spray them to combat webworms (Dipel® & other Bt-containing insecticides are organic-certified by OMRI), and like any fruit tree, you will need to keep them well-watered in their early years, but otherwise you can just enjoy the sweet, rich harvest and the natural beauty of these trees.
Figs & Pomegranates: Cold-hardiness and soil drainage are the key considerations for these species. Both originate in dry, warm climates, so it is not surprising that choosing a site that drains well and is somewhat protected in the winter will improve your chances of success. You also need to be sure that the fig cultivars you choose don’t require pollination. ‘Celeste’, ‘Brown Turkey’, ‘Desert King’, Scott’s Black, and many selections from the LSU breeding program (Scott’s Black is one) do very well here. Planting pomegranates along a South-facing wall of a building may be needed to get reliable fruit production because winter dieback can be severe.
Pie cherries: Chilling requirement is a major consideration for pie cherries. We just don’t get enough hours of effective chilling hours here for some cultivars. If you are lucky, ‘Surefire’, for instance, will sometimes produce a nice heavy crop, but inevitably it will experience a winter of insufficient chilling and will then flower and leaf sporadically, finally dieing altogether. ‘North Star’ and ‘Carmine Jewel’ are recommended for our climate. ‘Montmorency’ is intermediate. It’s more reliable and longer-lived than ‘Surefire’, but less well adapted than ‘North Star’ and ‘Carmine Jewel’. ‘Balaton’ also appears to need too much chilling for our climate. Birds are also very fond of all cherries and sometimes netting the trees is required to get much of a crop.
Muscadines: You will need some sturdy trellis or other structure for them to grown on. Otherwise, these are pretty carefree after they are established.
Pawpaws: Some shade for young trees and patience for them to get established. Otherwise, pawpaws are one of the easiest to grow and lowest maintenance fruit crops. The biggest problems I’ve experienced after pawpaw trees are established are mammalian pests (deer, raccoons, possums and people) stealing the fruit as it ripens and poor pollination. Fencing and exercising your Second Amendment rights can be useful for repelling mammals. Various creative and potentially disgusting pollination enhancement techniques such as hanging dead animals in your pawpaw trees during bloom have been practiced. Pawpaws are pollinated naturally by flies, so the rotting carcasses attract the pollinators. I prefer to use a camel-hair paintbrush to collect pollen from flowers on one cultivar and then apply them to receptive pistils on a different cultivar. This works quite well and reduces the number of calls to the police that your neighbors make.
The pollination story, though factual, is meant somewhat as entertainment. The flowers are dark purple and thus inconspicuous and they don’t attract enough flies on their own for you to notice. Furthermore, the trees are quite ornamental, with their large pendulous leaves that often turn a beautiful pure yellow in the autumn. The ripening fruit is also wonderfully aromatic, which is why deer and other critters are so attracted to them. Before planting pawpaws, you should taste one. A small percentage of the population is allergic to the fruit. The rest of us can enjoy a fantastic, tropical-like custard-textured fruit like no other. Folks compare the taste to mangos, bananas, papayas and other tropical fruits, but really a pawpaw tastes like a pawpaw.
Rabbiteye blueberries: Rabbiteye blueberries need very little care, but they do have a few special needs. Blueberries prefer acidic soil, so avoid planting them next to the foundation of a house or in well-limed soil. Also, it is recommended to use neutral or acidifying nitrogen sources, such as ammonium sulfate or cottonseed meal to boost growth. Their root systems are shallow, so mulching them well and keeping the weeds away from them, especially when they are young is very helpful. Also, even mature blueberries may require irrigation sooner during drought periods than other fruit crops. Although my family and I grew blueberries commercially and for home use for many years without any spraying, some pests and diseases now threaten the crop more frequently. Probably the worst threat is an newly-introduced fruit fly called the spotted wing drosophila. This is an especially difficult pest to deal with because it attacks fruit just before it ripens, obviating the ability to use many sprays with toxic residues so close to consumption.
Apples: Apples are so versatile, it is no wonder that they have become the world’s favorite temperate fruit (http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-29452011000500015). They are genetically well-adapted to a wide variety of climates, though you do have to take care to match the right apple cultivars with your specific climate. Here in the Piedmont, our hot humid climate makes some apples that are high-quality in cooler climates turn to mealy, tasteless mush in our searing summer heat. We also have more disease and insect pressure than those up North or on the West Coast. The biggest disease and pest problems are fireblight, cedar-apple rust (CAR), and codling moth. You can spray for cedar-apple rust and codling moth, but there isn’t much you can do against fireblight except choose resistant cultivars. (Yes, one can spray antibiotics like streptomycin or tetracycline, but these sprays have only limited effectiveness and it just seems extreme to do this when one can find excellent-quality cultivars that are quite blight-resistant.)
If you don’t have
red cedar trees in your area, you will probably not have any
cedar-apple rust because this fungal disease requires junipers, like
red cedar, to complete it’s life cycle. If you have a large
property and can eliminate the red cedars near your orchard, you can
greatly reduce the damage of this disease. Unfortunately, most folks
don’t have this option and cedars are prevalent. There are also
several good apple cultivars that are resistant to CAR, including
‘Mollies Delicious’, ‘Priscilla’, ‘Redfree’ and ‘Granny
Smith’. ‘Goldrush’ and ‘Pixie Crunch’
are two otherwise
very nice apples that are highly-susceptible to CAR. I had
previously listed "Williams Pride' as CAR-resistant, but as my tree got
older, I see increasing damage each year and now must agree with
University of Arkansas' assessment in this regard.
For codling moth, you will have to spray or you will have a high percentage of wormy apples, many of which will drop to the ground before they are ripe. Surround® works quite well to control codling moth, if used appropriately, if you want to grow organic apples. If you don’t mind non-organic fruit, several insecticides, including Imidan® and Malathion work well also.
Pears: The two biggest problems for pears, especially for high-quality dessert pears, are fireblight and codling moth. Fireblight is a bacterial disease that will kill the entire tree of susceptible cultivars. Unless you enjoy disappointment, please don’t even try to grow ‘Bartlett’ in our climate. I once planted a ‘Bartlett’ tree in Georgia that had mislabelled as a different cultivar. I actually got one crop of nice pears from it. However, the next year, the tree died in spectacular fashion, all of the new growth turned black and curled as if the tree had been hit with a flamethrower and the larger branches and trunk oozed massive quantities of reddish-brown bacterial slime. Fortunately, pear breeders have developed several blight-resistant cultivars that produce high-quality pears. If you like European-style buttery-textured pears, then ‘Mericourt’, ‘Ayres’, ‘Maxine’, ‘Potomac’, and ‘Warren’ are good choices, though ‘Ayres’ and ‘Warren’ are male-sterile, so you’ll need another pear to provide pollen. Asian-style pears that are blight-resistant include ‘Meadows’ and ‘Shinko’. A few blight-resistant pears, like ‘Spalding’ and ‘Green Jade’ (renamed Crisp ‘n Sweet™) are intermediate in that you can eat them when they are picking-ripe from the tree and they are firm and juicy like an Asian pear, or let them mellow off the tree like a European pear and they will become buttery-fleshed.
Sweet and Duke
cherries: Like pie cherries, you need to select cultivars that
medium-low chilling requirements in our region. Except for
late-ripening cultivars like ‘Hudson’, cherries are naturally
resistant to curculio because the fruit simply expands so fast that
the curculio eggs are crushed before they can hatch. However, brown
rot can still be a problem because curculios still lay their eggs in
the fruits, thus introducing brown rot spores and some cherries are
subject to cracking, especially if there is rain during the ripening
period. ‘Yellow Sweet Spanish’ seems especially susceptible to
brown rot among the cultivars I’ve grown. ‘Van’, ‘Nugent’
and ‘Lyons’ have done well for me, including having minimal brown
For best results, it is recommended to spray sweet and Duke cherries with a fungicide to control brown rot and cherry leaf spot, a debilitating fungal disease that attacks the leaves. In areas where domestic cherries have not been grown, you may not have much damage from cherry leaf spot until your trees are several years old. Once the disease is established, it will return every year unless a good fungicide spray program is implemented.
Another disease that can be devastating to sweet cherries is bacterial canker. Trees afflicted with this disease will suddenly wilt and die, often with a bacteria-laden ooze emerging from the trunk. There is little you can do to treat bacterial canker. The best prevention is to choose resistant or tolerant cultivars. Avoid ‘Hedelfingen’ and ‘Emperor Francis’, ‘Merton Bigarreau’. Cultivars that seemed more tolerant in my experience included ‘Black Tartarian’, ‘Starkcrimson’ and ‘Craig’s Crimson’,‘Yellow Sweet Spanish’, ‘Van’, ‘Nugent’ and ‘Lyons’.
Plums: For the Southeast, native P. augustifolia, Japanese P. salicina and hybrids between these two species generally fare best in our climate. European plums can also be grown, but, in addition to the problems common to all plums, tend to be more likely to be susceptible to bacterial canker (see sweet cherry section) and some need more chilling hours than our winters provide.
Nectarines: The two biggest problems with peaches and nectarines
the curculio/brown rot complex and peach tree borers. Borers can be
adequately controlled using well-timed applications of predatory
nematodes, but the curculio/brown rot complex will require regular
spraying, unless you limit your harvest season to only the extreme
earliest-ripening cultivars like Flordaking and Florida Dawn.
A nectarine is just a fuzzless peach. Just one allelic difference will change a nectarine to a peach. This very small genetic difference can impact the care required, however. Without the fuzz, nectarine fruits tend to be somewhat more susceptible to the dreaded plum curculio and the brown rot fungus they carry. On the plus side, because nectarine skin is smooth, one can use Surround®, which is an OMRI-certified and effective (when used properly) insect repellent to protect your nectarines and can just wash off the clay when you want to eat them. You can use Surround® on peaches, too, but it is impossible to wash the stuff off, so you will have to peel your peaches before eating, unless you like the mouth-feel of fine sand when you eat fruit.
Both peaches and nectarines can also be afflicted with bacterial spot, which can defoliate trees prematurely and shorten their lifespan. Fortunately, there are many cultivars that produce high-quality fruit on bacterial spot-resistant trees. Almost all new cultivars bred in the Southeastern U.S. are somewhat resistant to bacterial spot. Cultivars I’ve grown that seem to be quite bacterial spot resistant include Flordaking, Florida Dawn, Reliance, White River, Nectar Babe, Eldorado and Sweet Bagel. Red Baron and Peregrine are pretty tolerant as well. Cultivars that are quite susceptible to bacterial spot include Indian Blood Cling, George IV and, to a lesser extent Indian Blood Free. Keeping the trees otherwise healthy can allow you to get several years of nice crops even with some of the susceptible cultivars. Only George IV is so susceptible that I wouldn’t recommend attempting to grow it in our climate.
Another disgusting disease of peaches and nectarines is peach leaf curl. Luckily, you are unlikely to see this disease in our hot climate except in unusually cool wet Springs. Some cultivars, like Indian Blood Free are resistant to the disease as well.
Designing your Orchard for Ease of Maintenance
1) Site selection. Any respectable extension service will give you a lengthy explanation about air drainage and how you should site your orchard on a slope with northern or eastern exposure. That's all true in an ideal world, but let's face it, most people have a house and a yard and little choice but to make the best of whatever exposure they have. If you have a nice northern slope available, use it. Second choice is an eastern exposure. A southwestern exposure is the worst choice, but if that's all you've got, it's not the end of the world. If you only have a southwestern exposure site, then you can help your trees a bit by painting the trunks on the southwest side with whitewash or an interior latex white paint diluted half and half with water. Don't use oil-based paints or exterior latex paints, which usually contain anti-microbial additives that can be phytotoxic.If you have the luxury of some choice in site selection, the soil type and fertility are also very important. The primary consideration is proper drainage. If water stands in the area for longer than a day or so after heavy rains, it may be best to find another site, tile the area so that it will drain, or just not plant fruit trees. A moderately-fertile, well-drained loamy soil is ideal, but you can grow plenty of nice fruit on clays and sandy soils as well. Dry soils can be more easily overcome by adding water and mulch than a wet soil can be amended to increase drainage.
and Pest Control
Dates listed are rough and will vary according to your local microclimate and by year. I’ve tried to list more reliable signs that the trees will give you where it makes sense.
Amounts of spray material listed assume you are using something like an SPS backpack sprayer. Many spray guides listed by manufacturers or universities speak in terms of active ingredient per acre, which is a bit confusing for a small orchardist or backyard hobbyist. I’ve attempted to do the conversions and they have worked for me.
Conventional Spray Program:
1. February (when trees are dormant, or buds are just swelling, but no tender tissue of new growth is open yet): Dormant oil spray. Probably the most important spray all year. You are knocking down pests at the egg stage, mostly and early in the season when their numbers are relatively low. It isn’t sufficient by itself to produce high-quality fruit, but it is important. Apply when temperatures are above freezing (35-45°F) according to the directions on the label. One can also mix in baking soda at a rate of ˝ box/ 4 gallons of spray (=1.75 oz or 50g/ gallon) to help control various fungi. Baking soda (sodium bicarbonate) is readily available, but research suggests that potassium bicarbonate is even more effective (https://attra.ncat.org/attra-pub/viewhtml.php?id=126).
2. March-April (Petal fall- trees are no longer blooming and thus attracting pollinating insects like honeybees): 0.75 Tbsp Imidan® 70-W (insecticide) + 0.5 Tbsp Pristine® 50 WP (fungicide) per gallon of water. You may also find it beneficial to include 1 Tbsp chelated calcium, such as calcium lactate or calcium acetate per gallon, especially if you are spraying ‘Honeycrisp’ apples or early-season peaches or nectarines. This calcium addition is not for pest or fungal control, but for feeding the rapidly-developing fruitlets. Even if your soil has plenty of calcium, there are situations where calcium transport within the plant becomes limiting. ‘Honeycrisp’ is defective in calcium transport and early-season peaches have a very high need to pump calcium into the young fruits quickly to avoid split pit.
3. April-May (3-4 weeks after spray 2): Imidan + calcium (if needed) as for Spray 2 + a fungicide from a different chemical family than Pristine®, which is a combination of boscalid and pyraclostrobin. Pristine is a wonderfully-effective fungicide- the first year I used it, I had only a single peach fruit with brown rot in the whole orchard! However, fungi are resourceful at surviving, so it is best to switch among fungicides with differing modes of action to prevent the buildup of fungicide-resistant fungi. For this reason, if you use Pristine or another strobilurin family-fungicide, alternate it with one from a completely different family. Captan (also known as Orthocide, Clomitane, Vancide 89, Agrox and Merpan) is one good alternative fungicide that is readily available.
4. For the remainder of the season, until the point at which you stop spraying to allow for harvest, continue alternating Spray 2 and Spray 3 (or other insecticide + fungicide combinations- there are many effective ones, I only use those that I have used most commonly as an example). The point at which you stop spraying is determined by the more-conservative of two factors, 1) the pre-harvest interval of the chemical you are using AND 2) your comfort level. When using conventional chemical sprays, I always carefully read the label to find the pre-harvest interval recommended for that product, then I stop 1-4 weeks prior to that because it makes me feel better about the safety of the fruit I am about to harvest.
Organic Spray Program:
1. Dormant oil/ bicarbonate spray as for Spray 1 in the Conventional Spray Program.2. Petal fall: Surround (insect repellent) + Sulfur (fungicide) + chelated calcium (if needed- see above). Neither Surround nor Sulfur are compatible with oil-based sprays. Oil reduces the effectiveness of Surround and the combination of sulfur and oil is phytotoxic. However, Surround and sulfer together make an effective spray. One may also substitute bordeaux mixture for the sulfur. Like for conventional sprays, it is a good idea to alternate different (non-oil-based) fungicides to reduce fungal resistance. Note that the first time you spray Surround, you need to apply three coats. Basically spray once with the Surround + fungicide, then again with Surround only after the first coat has dried and then again when the second coat dries. After the first triple-coat of the year is applied, you only need to apply as a single coat per spray.
3. Subsequent sprays: Re-spray Surround + alternating fungicides + calcium after each rain or every couple of weeks, even if no rain falls in order to keep the surfaces of the growing fruit covered. Starting in mid-summer, it is a good idea to mix in an insecticide like Javelin (Bt-based), spinosad or rotenone to kill lepidopteran pests. Rotenone will also kill Japanese beetles. The pre-harvest interval for organic-certified sprays tends to be very short or even non-existent, in some cases. One can also substitute Serenade for other fungicides late in the season. It is not as effective as sulfur or copper-based sprays, but once diseases are under control, it will provide some protection.
Neem? In my experience, neem-based sprays have some effect on
reducing some fungal diseases and will kill soft-bodied insects like
aphids. However, neem alone is not effective enough to control
major pests like curculio, Japanese beetles and codling moth. If
you don't use Surround, then neem-based sprays can be a useful part of
an organic spray program. If you grow pears, avoid an enhanced
neem product called Azera®. Several pear cultivars are very
sensitive to this product. It will kill the leaves on these
sensitive cultivars and completely defoliate the trees and kill any
Other practices for pest and fungal control:
While all these fit within an organic pest and disease control program, they are good practices for any grower.
1. Sanitation: Clean out diseased and dead wood from growing and dormant trees. For instance, fireblight can be controlled by pruning out affected tissue, being sure to make the cut 6 inches below the visible blight damage. Pick up and compost any fallen fruit. Remove brown-rot mummies from stone fruit trees and burn them.2. Preventative Japanese Beetle Control: Apply milky spore to the orchard floor and any surrounding grassy areas that you have legal access to. It will take about six applications over a couple of years, but if you are not next to large tracts of grassland that you cannot treat, then you will see a dramatic reduction in Japanese beetles. One of my orchards is rather isolated by wooded tracts and my Japanese beetle population went from an annual horrible infestation that would defoliate all grapes, cherries, and severly damage apples and plums, to only being able to find 10-12 beetles per year in the entire orchard. Another orchard is bordered by pastures that belong to others and I continue to have Japanese beetle problems there. Milky spore kills underground Japanese beetle grubs, but doesn't kill adult beetles. I've tried various organic sprays to kill adult beetles. Pyola and neem were both touted by various folks as being effective at killing Japanese beetles. My experience of these products can be summarized thusly: Pyola gives you shiny beetles, neem gives you shiny beetles that smell good. The beetles appetite remains unaffected.
3. Predatory nematodes for control of peach tree borer: It helps to place pheromone-laced traps in the orchard to monitor when to apply the nematodes. The goal is to have swarms of active nematodes around the base of your peach trees when the peach tree borer female has laid her eggs and when those eggs hatch. The newly-hatched borer grubs are not protected inside the peach tree's roots yet and so can be more easily attacked by the predatory nematodes. The pheromone traps will capture male borer moths, which appear a week or so before the females show up. Buy the nematodes when you see the first males appear in your traps and apply them as soon as possible after they arrive. You may have to water them in a bit, if they arrive in dry weather. I use the two-species combination in the Sf/Hb nematode product sold by Arbico Organics.
4. Mite control predators, especially for pear blister mite and outbreaks of spider mites. Different predators are active under different conditions. However, the pear blister mite is buried inside the pear leaf tissue for most of the year and therefore protected from predators. The pear blister mite's Achilles heel is the early Spring, when it must migrate from the fallen leaves shed by the tree the previous Fall up to the new leaves emerging in the Spring. Phytoseiulus persimilis, applied in late February- early March, when leaves are just emerging made a noticeable difference in my orchard. It doesn't completely eliminate the pear blister mite, but damage is greatly reduced. I've also noticed that generally-speaking, European pears have some natural resistance to pear blister mite, whereas the Asian and Asian hybrids are often more damaged.
5. Cedar-apple rust/ pear rust/ quince rust prevention: These rust diseases all require spending part of their life cycle on junipers, most-commonly red cedar trees, to survive. The disease can't be spread from fruit tree to fruit tree, it has to infect a cedar and then the spores from the cedar can infect the pome fruits. Thus, clearing all cedar trees from in and around your orchard will greatly reduce or even eliminate this serious disease threat.
prevention: Armallaria is an underground fungus that attacks tree
roots. As it is growing in the tree roots, it appears as a black
shoestring-like material. Typically, you only notice
honey-colored mushrooms, especially near the base of the afflicted
tree. Armallaria is often fatal to the fruit tree and it attacks
all species of tree fruits. Pawpaws have been reported to have
better-than-average tolerance. Usually this fungus attacks forest
trees, so, if possible, it is best to plant your orchard in an area
that has been in grass for at least 15 years because grass doesn't
support armallaria. If you must plant fruit trees in soil that
has been growing forest trees, you can give them a better chance of
surviving by inoculating the roots with beneficial mycorrhiza when you
set them in the ground. Mycorrhiza are also beneficial for
general plant health in soils that have been mistreated by construction.
The North Carolina and Georgia Extension Services are excellent sources of useful information for growing fruit in this area. (I’m sure Clemson, too, but I haven’t had the privilege of living in South Carolina yet). However, I disagree with some of their cultivar recommendations. For instance NC State includes the ‘Empire’ apple in its recommendations and this Macintosh-derived cultivar is poorly adapted to ripening in our heat and is too susceptible to fireblight, in my opinion. Furthermore, their recommendations of disease-resistant apples is a bit outdated. They list Redfree, Prima, Priscilla, Jonafree, and Liberty cultivars for disease resistance. These are all good cultivars, but ‘Jonafree’ is quite susceptible to cedar apple rust in the Southeast, despite its resistance further north and ‘Prima’, ‘Priscilla’ and ‘Jonafree’ have largely been supplanted by newer cultivars of even higher-quality such as ‘Williams Pride’, ‘Goldrush’ (albeit this one is also susceptible to cedar apple rust) and ‘Enterprise’. I must add that if you are a fan of how the old-fashioned ‘Red Delicious’ tasted, you will like ‘Priscilla’. I personally have grown all of the resistant cultivars listed by NC State and like them all for fresh eating.
North Carolina: https://content.ces.ncsu.edu/producing-tree-fruit-for-home-use
‘HoneySweet’ plum information: https://www.ars.usda.gov/oc/br/plumpox/index/