Common Disease Problems
Bacterial Canker: Gummy, water-soaked cankers appear on branches and the trunk. Fruit develops with dark, sunken areas. This causes them to be more susceptible to brown rot. Cool, wet weather promotes development of cankers after blooming. Burpee Recommends: Cut out diseased wood. Contact your Cooperative Extension Service for recommendations.
Bacterial Leaf Spot: First signs are small translucent spots with a broad yellowish edge that slowly enlarge and become angular or irregularly circular with a reddish center. It thrives in cooler temperatures. The disease may also affect and disfigure flower heads. Burpee Recommends: Remove infected plants. Rotate crops with plants in a different family. Avoid overhead watering. Do not work around plants when they are wet.
Black Knot: Twigs and branches exhibit hard black knobby growths. This eventually girdles and kills branches. Burpee Recommends: Cut out diseased wood. Contact your Cooperative Extension Service for recommendations.
Crown Gall: This is caused by a bacteria and causes galls (masses of plant tissue) to form on roots, root crowns, stems and branches. The galls can interfere with the ability of water to move through the tissue, affecting plant vigor and causing stunted plants. Burpee Recommends: There is no cure for this disease; remove and destroy infected plants. Do not divide or propagate infected plants.
Scab: Dark spots form on leaves and fruit. Water soaked lesions gradually turn brown in the center with a lighter colored margin. Cracking on the fruit can occur. Burpee Recommends: Contact your Cooperative Extension Service for recommendations.
Common Pest and Cultural Problems
Japanese Beetles: Burpee Recommends: Hand pick early in the morning into a bucket of soapy water.
Leafhoppers: Leafhoppers cause injury to leaves and stunt growth. They also spread disease. Burpee Recommends: Remove plant debris. Use insecticidal soaps. Consult your Cooperative Extension Service for other insecticide recommendations.
Lygus Bugs (Tarnished Plant Bug): Lygus bugs are ¼ inch long and are green or brown with yellow markings. Nymphs are flightless and smaller than the adults. They suck on stem tips and flower buds and inject a toxic that deforms roots, stems and ruins flowers. Burpee Recommends: Because lygus bugs over winter in garden debris, remove all debris after the first frost. Contact your Cooperative Extension Service for insecticide recommendations.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Thrips: Thrips are tiny needle-thin insects that are black or straw colored. They suck the juices of plants and attack flower petals, leaves and stems. The plant will have a stippling, discolored flecking or silvering of the leaf surface. Thrips can spread many diseases from plant to plant. Burpee Recommends: Remove weeds from the bed and remove debris from the bed after frost. Check with your Cooperative Extension Service for pest controls.
Do I need two different plum varieties for cross pollination? Some varieties need two varieties for cross pollination and some are self-fruitful. Check your specific variety to see if you need a pollinator.
When will my tree bear fruit? Trees should bear fruit in 3-4 years, with full fruiting in 5-7 years.
Can I grow plum trees in my zone 10 garden? No, unfortunately plums requirecold winter temperatures and are not recommended in warmer zones than zone 8 or 9.