Apple growing in the Pacific Northwest can be very fun and rewarding. Unfortunately, several diseases due to the climate of the Willamette Valley can be challenging for residential and commercial orchard production, as constant rainfall and cool spring and summer conditions favor the development of fungal and bacterial diseases. In places with less spring and summer rainfall and plenty of sunshine, such as North Central Washington, these cases are much rarer than we have here in Portland. This weather pattern is the result of environmental variables known as three diseases. The triple disease is an interaction between a susceptible host, a virulent pathogen, and a favorable environment. All three elements are necessary for any disease to occur. While organic farming focuses on controlling disease after it occurs, environmental disease management focuses on the conditions that predispose plants to disease. To better understand the most common diseases in Portland area orchards, here is our description of the top 9 bacterial and fungal diseases and the traditional and pest control methods used to prevent and treat them.
- Bacterial diseases
- Fire blight
- Pseudomonas bacterial canker
- Fungal diseases
- Apple Scab & Pear Scab (see scab blog)
- Perennial Canker/Bull's Eye Rot/Anthracnose
- Powdery Mildew
- Speck Rot & Sphaeropsis Rot
- Brown Rot
- Silver Leaf
- Shot Hole Blight
- Leaf Curl
Fire blight is a disease that affects both apples and pears. It is caused by the Erwinia amylovora, which grows between 50° and 100°F and grows rapidly between 25° and 35°C. Bacteria overwinter in roots (infected gums) that were infected last year. Before and during germination, bacteria are released from the canker and dispersed by rainfall, as well as insects, which are attracted in the runoff and transmit the pathogen to the pistils as they feed on the root stock. 
The viruses multiply within 4-8 days of flower opening, and if the fruit is successfully colonized, the virus can spread to the cambium membrane between the stem and the tree, killing the host tissue. Active winter cannabis can produce enough bacteria to infect a large number of seedlings per acre, so it is important to prune dormant cannabis and remove damaged plants from the garden. Working with neighbors to reduce the spread of disease can make the climate healthier and more productive for all. One way to prevent pests is to select resistant shrubs and cultivars, choose high-elevation nurseries for non-resistant pest training, and train trees to limit freezing and increase wind and sunlight to ward off insects and pathogens., flowering and soil fertility, and leaf nourishment. Concentrating spring and early fall pruning efforts and reducing dormant pruning can reduce summer overgrowth and thus reduce thatch. Especially when cutting in the summer, it is important to keep your tools clean. In the summer, trimming more than 12 inches of the top of the visible tarp can help prevent further damage. In extreme cases, electrospray and the use of oil on the back of a can reduce bacteria and lubricate the body, which can reduce winter bacteria. Plants with a short vegetative cycle generally perform better than varieties with a short vegetative cycle and plants with a long vegetative cycle.
Fire blight resistant – Apple Rootstock- Bernali, Budagovsky 119, Budagovsky 490, Geneva Series, Malling 7, Vineland: 1,2,5,6,7 Fire blight apple varieties* - Akane, Arkansas Black, Britemac, Carroll, Classic Good, Cox's Orange Pippin, Scarlet Gala, Stark Splendor, Gourmet Swiss, Turkey, Delicious, First Red One McIntosh, Gold Rush, Gold Spur, Harolsen, Honey Crisp, Jamba , James Grieve, Jonafree, Memories, Kidd's Red Orange, Freedom, Laurared, Luster Elstar, Lightgolden, Macfree, Macspur, Empire, Melba, Melrose, Mor Spur Mac, Nova Easygro, Nured Delicious, Nured Winesap, Ozark Gold, Perfect Criterion of Spur , Pioneer Mac, Prima, Starkspur, Starking, Starkrimson, Scarlet Spur, Sturdeespur, Topspur, Dixie, Dana, As, Red Chief, Viking, Wellington, Williams Pride, Williams Red. A bacterial canker is a virus that affects cherries. It is caused by the bacterium Pseudomonas syringae and is sensitive to air and water. Bacteria overwinter in crabs and their host cells. Dark crabs on trunks and branches grow in spring. The main symptom is drooping and dark irritation on the main stem branches and saddles. Infected tissue sometimes produces pus, and cancer can spread to the arms, causing the victim to die. The affected areas will lead to dead leaves, causing the leaves to yellow, fall, and die later in the summer. Bacteria are spread by wind, rain, insects, pruning equipment, or infected roots and tubers. The condition may be physical and should not cause obvious symptoms. Traditional pest control methods include injuring plants, pruning weeds during drought, cleaning tools regularly, and removing severely infected plants. Some fruit trees prune and burn cannabis before it flowers. Additionally, the virus colonizes many types of grass and weeds, so keep grass and consider clover and sedge as these cover crops help reduce bacterial worm counts.
In young trees, infection is more likely to occur where there is tissue damage, frost, and frost, insect damage, wood chips, or leaf shards. In older trees, the disease persists after the tops are cut. Bacterial cancer is reduced when potatoes are covered with white cotton to reduce sun damage. Plants grown in well-drained soil are more susceptible to water and nutrient deficits than stressed plants. All cherry pruning should be done during the summer dry season when possible. Electrical radiation has been shown to cause increased damage to bacterial cancer cells. Bacterial Canker Resistant Cultivars- Rainier, Regina, Sandra Rose Apple anthracnose, Bull's Eye Rot, and chronic canker are common fungal diseases of the genus Neofabraea. From plants - cranapples, most pomegranates and stone fruits, shrubs, ginger, and rowan. Dung produces smaller branches and the first rotten cows. During the rainy season, the fungus spreads on ripe fruits and young branches. In summer, the first sign of infection is a small brownish-red spot. Canker development and new enlargements spring, followed by a fissure around the wrist where the underside of the wrist compresses, twists, dies, and falls away, leaving an exposed dead "short" area. In the rainy season, mushrooms ripen and are blown away by rain and wind in early autumn. In the case of honeycomb rot, the disease process is manifested as circles of round spots on canned fruits with later fruits and fungal bodies in the center of the circle. Perennial hemp is most common in areas with hot, dry summers and harsh winters east of the Cascades. Perennial crabs grow in interlocking circles because the growth is renewed each year with small gallons of green apples around the flowering edges of existing crabs. 
These galls become new sites of infection and eventually cause severe dehydration or death in the host. Cultural control is primarily based on the identification and aggressive removal of infectious tissue at the needle site, as well as amputation and cauterization of infected hands. Severely damaged trees must be removed. Powdery mildew is a fungal disease that destroys cherries, apples, pears, apples, blackberries, strawberries, grapes, peaches, and many other vegetables. Unlike many other diseases, powdery mildew does not require hydrocarbons to grow and is limited by sources of clean water. Frost overwinters on leafy areas and remains on leaves until winter on other plants. Powdery mildew is easily recognized by the presence of black and green mycelium on leaves, flowers, fruits, and stems. Cultural Control - Provide adequate air and sunlight when cutting off excess foliage. Sick and very damaged bushes are sleeping as if they come out in early spring. Crops susceptible to powdery mildew - Apples: Gravenstein, Jonathan, Roma Beauty, Newton Yellow. Cherries: Bing, Black Tartar, Rainbow. Peach: Elegant Lady, Good Time, Faye Elberta, Summerset. Plum: Black Beauty, Gull, Kelsey, Wickson. Speck Rot and Sphaeropsis Rot are post-harvest fruit rots caused by the fungi Phacidiopycnis washingtonensis and Sphaeropsis pyriputrescens, respectively.
Spot rot affects the apple and Manchurian crabapple variety, which is highly susceptible to the disease and is an infectious host for commercial orchards, often planted as pollinators among market apple trees. Sphaeropsis rot affects apples and pears, especially D'Anjou pears and Red Delicious, Golden Delicious, Fuji, and Granny Smith apples. Manchurian crab is highly susceptible to sphaeropsis rot and speck rot. Both diseases live in dead tissue and cause branch death and develop into cankers and small black fruiting bodies containing spores that are spread by rain. Fruit damage caused by sphaeropsis rot results in a distinct bandage-like odor in the flesh and spot rot is characterized by dots around the end of the calyx or stem of an apple. Cultural control involves pruning both stems to allow them access to sunlight and air and to remove dead and diseased twigs, branches and fruit from the orchard. Brown Rot flower and branch disease occurs on stems of Monilinia fructicola and occasionally on Monilinia laxa and various pome and stone fruits. The disease remains in the mummified fruit over winter, and spores are released into the air when the plant flower. In case of infection, the spores and the surrounding leaves of young flowers collapse, gums and cankers protrude from the base of the flowers, and the branches have spots and dark edges on the branches. Infection of ripe fruit occurs in damaged tissue and becomes evident as the fruit ripens in colder temperatures. Cultural control—The disease is controlled by the same fungal control methods of open pruning and removal of infected fruit and shoots. The disease can be caused by rapid storage and rapid cooling to low temperatures, especially before it is well established in the fruit. Silver leaf on the cherry Silver leaf mold is a fungal disease that affects cherries, apples, pears, peaches, plums, nectarines, blueberries, smoothies, willows, and poplars. It is caused by Chondrostereum purpureum, which damages roots, trunks, branches, and shoots.
The fungus is a saprophyte, which means it lives in dead tissue. It can become an active parasite if it has a point of entry into living tissue, such as pruning shears, insect damage, mechanical damage, or winter damage. As the name suggests, when healthy, dark green leaves silver on one or two smaller branches, they eventually develop into dust mites and soon infect the larger branches and eventually die. When a branch dies, the mushroom's fruiting body radiates from the dead tissue, producing a supporting mushroom that is usually salmon pink to purple on the underside, layered, and 1 to 3 inches wide. Cultural control – burning trees to prevent deforestation, direct tree felling, and during drought. Biological control of Trichoderma viride. Shothole or Coryneum Blight is caused by the fungus Thyrostroma carpophilum and affects cherry, peach, and apricot trees. This fungus on injured branches spreads lice and lice in the water. The holes in the leaves of infected plants are 1/4 inch in diameter. The lesions begin as yellow, red, or yellow patches, sometimes with a dark yellow tinge. As temperatures rise in spring, the pollen dies and falls off, creating lips, or "bullet holes," in the leaves. Crop control consists of pruning trees to maximize air and light transmission and reduce moisture. If you have cankers on the branches or stems, cut out the affected parts. Leaf Curl: Taphrina deformans, a fungal disease commonly found on stone fruit in and around Portland. If you have pears, you may have experienced this condition. 
Infestation continues through the winter on leaf and stems bacteria and, like the appearance of spores, occurs in spring when temperatures are between 50 and 70 degrees. The leaves can infect any new leaf that appears in the spring, causing the leaves to wilt and die within a few weeks. It affects the plant and thus fruit set and yield. The tree will likely shed all of its infected leaves by mid-summer, and the resulting new growth will look great. But damage and the passage of time will reduce the vitality and health of these plants. The best way to grow peaches, nectarines, and apricots in Portland is to plant a resistant variety nearby. Puget Gold Apricot, Frost Peach, Indian Free Stone Peach, Muir Peach, and Kreibich Nectarine are in maximum protection. Stay away from the redskin peach and its relatives as they are susceptible to disease. We recommend ingredients with careful labeling and safety precautions, including Liqui-Cop, Wettable Sulfur, Neem Oil, Potassium Bicarbonate, and Bacillus Subtillis. All of these are generally acceptable in organic food production, but should only be used after pollinator activity levels, dilution levels, and orchard size have been estimated. The use of organic chemicals on native fruit trees is minimal. It's always best to manage the long-term health of the garden and encourage beneficial insects and insects. The spray bottle we generally use is based on a recipe by Michael Phillips of Red Holistic Orchard: Add 1 gallon of water An ounce of pure neem (100% of this stuff is inactive at room temperature). A teaspoon of natural soap (with neem oil as an emulsifier). 3 ounces of fish juice. Add 1 cup of milk. Stir in 1 cup sea salt. Where we see temperatures of 50-70 degrees and lots of rain, add 4-6 oz, Organic Fungicide (Bacillis subtilis).