Apricots, problems
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Eutypa dieback—Eutypa lata
Eutypa dieback, also known as Cytosporina, gummosis, and limb dieback, causes limbs or twigs to wilt and die suddenly in late spring or summer with the leaves still attached. Rough dark cankers may develop at pruning wounds. The bark has a dark discoloration with amber-colored gumming.
Solutions
Eutypa dieback occurs when fungus spores are spread by rain and infect trees through pruning wounds. Remove infected limbs at least 1 foot below any sign of the disease. Prune during July and August after harvest. Ideally, pruning should be completed at least 6 weeks before the first fall rains. Wound treatments with fungicides, paints, or sealants have not been satisfactory. Cauterizing freshly pruned branches with a hand-held propane burner may prevent infection.Brown rot—Monilinia spp.
Seasonal development and life cycle—Brown rot
The fungus that causes brown rot survives the winter in infected twigs, inside dead, blighted blossoms that remain on the tree, or in dried, rotted fruit on the tree or on the ground. Spores are carried through the air by wind and splashing water to infect flowers in the spring.
Fruit is most susceptible to infection by the brown rot fungus when it is ripe. Most fruit rot develops during the month before harvest, although rot occasionally may develop on green fruit in early summer.Solutions
Remove and destroy fruit mummies and diseased plant parts promptly. This prevents the build-up of the fungus and helps keep rot below damaging levels. Prune trees to allow good ventilation. Furrow irrigate or use low-angle sprinklers to avoid wetting blossoms, foliage, and fruit. Plant varieties that are least susceptible; check with your local nurseryman.If you have had problems in the past, applications of copper-containing or synthetic fungicides such as myclobutanil at pink bud stage can help avoid serious losses. Additional applications when fruit starts to color may be needed if rainy weather persists. Do not apply copper compounds after bloom.
Read more about copper-containing fungicides.
Read more about myclobutanil.Shot hole disease (Coryneum blight)—Wilsonomyces carpophilus
Life Cycle
Solutions
Prune and dispose of infected tissue as soon as it appears. After leaf drop, inspect plants carefully and prune infected buds and twigs with lesions. Diligent sanitation and water management can provide adequate control where the incidence of shot hole is low. Avoid overhead sprinklers or use a low angle to avoid wetting foliage. Also, some varieties may be less susceptible. Where disease incidence is high, fungicides such as Bordeaux mixtures or fixed coppers may be applied. On peaches and nectarines, a dormant spray of copper in late fall will work well.Peach twig borer—Anarsia lineatella
Identification of speciesLife cycle
Damage
Larvae bore into the growing shoots of twigs and ripening fruit or nuts. Shoots and leaves wilt and die back one to several inches from the growing tips of twigs. In fleshy fruit, injury is usually superficial.
Solutions
Tolerate low levels of damage. The most reliable control for peach twig borer is a dormant spray of spinosador spinosad and oil, applied in winter to kill overwintering caterpillars on the tree branches. Spinosad or Bacillus thuringiensis, applied just as trees bloom and again a week later, also controls the pest. Avoid spraying during the growing season because it is difficult to time pesticide applications effectively. Sprays must be applied to control hatching larvae before they enter twigs or fruit.Read about other pests and diseases of apricots.