Crabapple: Plant Heath Care Recommendations
A Technical Report from The Bartlett Tree Research Laboratories
Crabapples (Malus, sp.) are a versatile and popular small tree for urban and suburban landscapes. More than 400 species and varieties of crabapple are available which represent a diversity of flowering and fruiting characteristics, growth forms and pest resistance.
Flowers produced in early spring are white, pink or red. Fruit which vary in size and color may cling to twigs into winter to provide interest and food for wildlife. Crown shape may be rounded, upright, spreading or weeping depending on variety. Dwarf crabapples which remain under ten feet in height are popular in containers where space is limited.
Eastern tent caterpillar
As with most members of the rose family, crabapples are host to many insect and disease pests. Common leaf-chewing insects include tent caterpillars, Japanese beetles, gypsy moth and cankerworms. Aphids, scale insects and spider mites damage leaves or branches by removing sap with their sucking mouthparts.
Fireblight is the most devastating disease of crabapple. Caused by a bacterium which infects through the blooms, fireblight causes branch dieback and even death of susceptible varieties. Foliage diseases including scab, rust and mildew can cause defoliation. While crabapple tends to tolerate these diseases, defoliation detracts from their appearance and vitality. Disease resistant varieties are available and should be utilized reduce the impact of these diseases.
Recommended Monitoring for Crabapples
|Winter||Corrective prune crown on trees where flower production is not a primary consideration. Otherwise delay pruning until after bloom.|
|Late Winter||Sample soil for nutrient and pH levels especially if deficiency symptoms are present. Prune out any deadwood. Apply horticultural oil for overwintering insects. Include bactericide with oil to suppress fireblight on susceptible varieties. Inspect root collar. Adjust or add mulch as necessary.|
|Early Spring||Apply first fungicide spray treatment to suppress scab and rust on susceptible varieties. Include bactericide with fungicide to suppress fireblight on susceptible varieties. Monitor for tent caterpillars, aphids, gypsy moth and other early season defoliators. Treat as necessary.|
|Mid Spring||Apply second fungicide spray treatment to suppress scab and rust. Monitor for aphids, scale crawlers, tent caterpillars and other early spring defoliators. Treat as necessary. Fertilize or amend soil as specified in soil test report. Prune out and destroy shoots with fireblight symptoms.|
|Late Spring||Apply third fungicide spray treatment for scab and rust. Inspect for aphids, scale crawlers and spring defoliators. Treat as necessary. Prune out and destroy shoots with fireblight symptoms.|
|Early Summer||Corrective prune crown if not done in winter. Inspect for aphids, scale crawlers, mites and Japanese beetles. Treat as necessary. Monitor irrigation and soil moisture to prevent water stress.|
|Mid Summer||Inspect for aphids, scale crawlers, mites and Japanese beetles Treat as necessary. Monitor irrigation and soil moisture to prevent water stress.|
|Late Summer||Inspect for aphids, scale crawlers, mites and Japanese beetles. Treat as necessary. Inspect irrigation and soil moisture to prevent water stress.|
|Fall||Remove fallen leaves. A soil applied systemic insecticide can be applied to suppress scale and aphid population the next year. This is recommended when these pests have been exceptionally damaging. Apply additional mulch as necessary. Ensure root collars are free of soil and mulch.|
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