| Fruit - May 2008
Please Note: All recommendations are for central Maryland. Time frames shift two weeks earlier in Southern Maryland and the Eastern Shore and two weeks later for Western Maryland. Check publications for further information.
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Culture
Fruit drop of tree fruits is a natural thinning phenomenon and usually occurs in June. Some earlier fruit drop may be caused by disease and insect problems, environmental stress and lack of pollination or fertilization. Pick up and throw out all dropped fruits. Mature fruit trees that produce no fruit may be growing in excessive shade or require a pollinator plant. Most apples, pears, sweet cherries and some plums require a pollinator plant.
All new fruit plants should be kept well watered for the first growing season.
Tender, tissue cultured strawberry plants can be safely transplanted now.
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Insects
Consider placing small plastic jugs in your strawberry rows filled with water, molasses and yeast to attract and trap sap beetles which are attracted to over ripe fruit. Pull the blooms off of newly planted strawberry plants for the first growing season. Mulch under and around strawberry plants to keep the fruits off the ground. Strawberry flowers must be cross-pollinated by bees to produce large, well-shaped fruits. Cover strawberry beds with bird netting or floating row cover before the berries become ripe to exclude birds, squirrels and other hungry critters.
Peach tree borer larvae that over-wintered in the lower trunks of peach trees are actively feeding on the cambial tissue, right below the bark. You will see entrance holes with thick sap or gum at the opening. The feeding of only a few borers can girdle and kill a young tree. A vertical cut with a very sharp knife can be made around the entrance hole in an effort to locate and kill the borers. Inserting a sharp thin wire into the holes may also spear the borers. Borers are attracted to stressed trees so keep your trees healthy to prevent damage.
Cherry fruit worm can be controlled with insecticide sprays once adult fruit flies are observed. This is usually the same time that fruits begin to show some color.
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Disease
Wet weather can lead to peach leaf curl problems. Peach leaves infected with this fungal disease will thicken, pucker and turn red, pink or purple. Rake up and dispose of fallen leaves. The affected trees will grow new leaves and should still produce fruits this summer. Spray your peach trees with liquid lime sulfur next spring when buds begin to swell.
Be prepared to spray fungicides during bloom on grapes that were damaged by black rot last year. Always use a fungicide labeled for the specific purpose intended and follow label directions.
The floricanes of June-bearing raspberries should be headed back at 3-4 feet to encourage lateral growth. Thin out new bramble shoots so that there is at least a 6 inch space between shoots. Tip the laterals of the fruiting canes of bramble plants to 12-18 inches. The skinny growth at the ends of laterals will not bear good fruit and will create a dense, unproductive canopy. Remove any bramble canes that show virus symptoms- small, curled, distorted or mottled leaves. Blackberry and black raspberry plants with leaves exhibiting dusty, orange pustules are infected with rust disease and should be dug up, bagged up and thrown out.
New blueberry leaves that are yellow are probably suffering from a lack of iron, due to soil pH above 6.0. Apply a chelated iron product to affected plants and add enough sulfur to drop the soil pH to the 4.5-5.0 range. A very light, 1 inch deep cultivation of the soil around blueberry plants will help reduce mummyberry disease. This common fungal disease causes blueberries to shrivel up and drop before they ripen. Fertilize mature blueberry plants each spring with 8 ounces of ammonium sulfate. Half should be applied during bloom and the other half when fruits begin to form. The nitrate form of nitrogen will damage blueberry roots. Keep your blueberry plants well-watered during dry periods. They are very susceptible to drought stress.
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