By: Amy Grant
Mayhaws are common trees native to the southern United States. They are a member of the Hawthorn family and have been prized for their delicious, crabapple-like fruit and stunning profusions of white, spring blossoms. Animals find mayhaws irresistible as well, but how about bugs that eat mayhaw? Deer and rabbits are mayhaw pests that can destroy a tree in no time, but does the mayhaw get insect problems? Read on to learn about pests of mayhaw.
Do Mayhaw Have Insect Problems?
While several mammals and birds enjoy the fruit of the mayhaw as much as people do, if not more, there are really no serious mayhaw insect problems. That said, there is limited information on mayhaw pests and management, probably because the tree is rarely commercially cultivated.
Pests of Mayhaw
While there are no serious pest threats to mayhaw trees, that is not to say that there are no pests. Indeed, the plum curculio is the most aggressive and can cause significant damage to the fruit. Plum curculio can be controlled with the use of a spray program as part of an integrated pest management program.
Other common pests, besides the deer and rabbits, that can affect maymaw trees, include the following:
- Flat-headed apple borers
- Hawthorn lace bug
- Leaf miners
- Apple maggots
- White-fringed beetles
These mayhaw pests may feed on the foliage, flower, fruit and wood of the tree or a combination thereof.
Of more concern when growing maymaw are diseases such as brown rot that can decimate a crop if left unchecked.
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Management and Control
Integrated pest management (IPM) strategies are effective in controlling leaffooted bugs. One important principle of IPM is knowing your "action threshold," and deciding when to intervene. Action thresholds are "levels of pest density or damage that result in consistently measurable losses in yield quantity or quality." Minor damage may not warrant any action except continued observation.
Cultural control methods are a strategy of IPM you can practice before pest problems arise. These gardening techniques help keep pests at bay by making your plants less appealing or available. In the case of leaffooted bugs, row covers can keep flying adults from entering and laying eggs. Keeping plants healthy, well-watered, and appropriately spaced are also cultural control methods.
If the damage passes what you consider an acceptable "action threshold," start controlling the pests with low-impact techniques. Always try the safest alternatives first. A good place to start is handpicking, a mechanical form of pest control. Destroying the eggs, nymphs, and adults by hand is a very effective method of leaffooted bug control. Dispose of any captured insects so they do not return to feed again.
Attracting beneficial insects is a form of biological control and another popular option for controlling these pests. Leaffooted bugs are preyed upon by several native parasitic wasps and flies, as well as assassin bugs (pictured below), spiders, and birds. If these beneficials frequent your garden, protect them so they can continue their work.
Assassin bug nymphs hatching. Photo by Megha Kalsi, University of Florida.
If you are unable to control leaffooted bug with cultural, mechanical, and biological control strategies, it may be time to consider a chemical control. But it is important to note that pesticides, while effective against leaffooted bugs in the nymph stage, may not be equally effective against adults.
When applying pesticides, spot-treat only. Use pesticides to treat the affected areas of a plant or landscape bed, not the whole yard. Avoid using broad-spectrum insecticides whenever possible. They're not selective, meaning they also kill beneficial insects, including bees. Instead, choose targeted products, which are designed to harm only specific pests. Read and follow all label instructions. Remember that the label is the law!
If you have questions about leaffooted bugs, pest management, or pesticides, contact your county extension office.
And for more information about specific yard pests, diagnosing pest problems, and controlling pests, visit University of Florida IPM online.
Hawthorn Leaf Blight
Hawthorn leaf blight is caused by the fungus Monilinia johnsonii and can cause severe damage to mayhaw leaves and fruit. This disease is similar to brown rot of peaches, which is caused by a different species of Monilinia.
Symptoms and Signs
Infected leaves wilt and turn brown. Infected fruit are hard and shriveled (mummified) and drop to the ground before reaching maturity.
Ecology and Spread
The fungus overwinters on mummified fruit. Spores released from mummified fruit infect leaf buds or newly emerging leaves. Spores produced on blighted leaves in the spring can infect blossoms. Fruit formed from infected blossoms mummifies and drops to the ground, where it will produce the spores that cause infections the following year.
Cultivars that have late leaf emergence or slow leaf growth and cultivars that bloom early or quickly are more likely to escape infection (Scherm and Savelle, 2003).
Selection of early-blooming cultivars or cultivars with late leaf emergence or slow leaf growth can reduce disease incidence by preventing the timing of spore dispersal from overlapping with the time that susceptible plant growth is present. Fungicide applications when conditions are favorable for disease development can help prevent hawthorn leaf blight (see Table 2).
Table 2. A guide to fungicides labeled and registered for use in Mississippi for management of fire blight, rusts, and hawthorn leaf blight on mayhaws.*
Apply at lower rate at 2- to 4-week intervals.
Begin applications at 20–30% bloom. Repeat at 7-day intervals or when conditions are favorable for disease.
Do NOT apply after petal fall.
Begin applications at 1–5% bloom and repeat as needed to protect open, untreated blossoms when conditions favoring disease development are likely to occur (every 2–7 days). Continue applications after petal fall on 7-day intervals while environmental conditions favor disease.