Dear Master Gardener: How do I protect my apple trees from apple maggots?
Answer: The most unwelcome insect pest for Minnesota-grown apples is the apple maggot. To help protect your apple trees from apple maggots it is very important to keep your garden area clean. Pick up and remove apples that fall during the growing season and put them in the trash. Do not compost them in your yard. Apple maggot infestation will be greatly reduced by removing overripe and rotten apples from around your trees.
Although it is time-consuming, a non-chemical method of preventing damage is to bag your apples in mid-June. This will protect them from apple maggots and other insects for the rest of the growing season so no spraying is needed. It is easy to do if you have small to medium-sized trees that can be managed from the ground or a short ladder. Thin clusters to one apple every six to eight inches, then enclose each marble-sized apple in a plastic sandwich bag with a zipper closure. Snip the bottom corners off each bag with a scissors so condensation can drip out. Leave the bag on until harvest.
Another option is to put up apple maggot traps, which are red spheres coated with Tanglefoot (a super-sticky substance). You will need one or two spheres for a small tree and five or more for larger trees. Place at least one trap on the side of the tree that faces a wooded area and a second trap on the south side of the tree. In order to catch apple maggot flies when they are first attempting to lay eggs, hang your traps in the trees by the end of June. Make sure to remove any leaves or fruit touching the traps. Check your traps weekly, clean off the captured insects and debris, and apply more Tanglefoot as needed.
Dear Master Gardener: I planted some lavender and was wondering if it will come back next year?
Answer: Lavender is a wonderfully fragrant plant and a great ornamental addition to the garden. It is hardy to USDA zone 5, so it should be treated as an annual in our area. Pots of lavender may be brought indoors for the winter. Lavender can tolerate hot, dry conditions better than wet, humid ones, so it is important not to overwater your plants. Growing it in damp soil promotes root rot and fungal diseases.
June Gardening Tips
• Early June is a great time to finish planting gardens, containers, and hanging baskets.
• Cut rose flowers early in the morning when it is cool and the top of the bud is starting to open. Make the cut at a 45-degree angle above an outward-facing, five-leaf leaflet with sharp, clean pruners.
• Move houseplants outdoors when nighttime temperatures are 55-60 degrees, as they will benefit from increased light and humidity. Keep them protected from direct sun. Heat and wind can dry them out, so check them often to see if they need water. Add fertilizer at half-strength every few weeks.
• You may need to replace early vegetables such as peas, radishes, leaf lettuce and spinach with quick maturing seeds or transplants. You can direct seed green beans (bush type), beets, green onions, or summer squash.
• As temperatures rise, allow your lawn to grow 2 ½ inches or taller before mowing it. Taller grass blades help shelter the crowns from heat and wind, protecting them from excessive drying. There is evidence that roots grow deeper when grass is taller. Allow clippings to fall back into the lawn where they will break down and recycle nutrients.
• Water your lawn deeply and infrequently when it shows signs of drought stress (dull color, blades curling inward, your footprints are obvious in the grass). Conserve moisture by watering early in the day when temperatures are lowest and winds have not picked up yet. Avoid late evening watering if possible because foliage that remains wet overnight is more prone to plant diseases.
• If you need to prune spring-flowering shrubs, such as rhododendron, azalea, lilac, forsythia, weigela or ninebark, do it right after they have finished blooming. Pruning later in the summer may eliminate much of next year's blooms.
• Anthracnose is a fungal disease that shows up almost every year on ash, maple and, sometimes, oak trees. It causes large dark blotches on leaves, many of which drop. Only rarely is it severe enough to damage trees. Rake up and dispose of fallen leaves. Fungicide is not necessary.
• Resist the temptation to cut or pull off or tie together the unattractive leaves of daffodils, tulips and other spring-flowering bulbs. Leave them until they are no longer green. Keep fertilizing until they are brown and withered because the foliage continues to gather energy to nourish the bulb for next year.
• To control height and create a bushier plant, keep mums and asters 6 inches tall throughout the month of June by pinching them back.
• Cut back Dicentra (bleeding heart) as the flowers fade. This will reduce reseeding and encourage new growth.
• Avoid overfertilizing your plants. Most perennials get all the nutrients they need from the soil. Top-dress established beds every three to four years by working several inches of compost into the soil surface. If plants are stunted or less vigorous you can give them a boost with a diluted solution (one-half the recommended amount) of liquid fertilizer.
• Check the upper and lower leaves and stems of your plants for aphids and mites. They suck out plant juices and cause leaves to turn yellow and brown. Spray leaves, especially the undersides, with a blast of water to dislodge these pests. If there are still too many, use an insecticidal soap (a soap formulated to kill soft-bodied insects that is not harmful to the plant or environment).
• Check pine trees for pine sawfly larvae that look like caterpillars. Knock them off with a blast of water from your garden hose.
• Create a butterfly garden with children by planting butterfly favorites: chives, butterfly weed, coneflowers, Liatris, yarrow, dill, zinnia, marigold, verbena and/or cosmos. Add a few rocks for sunning and a shallow saucer of water. A book your children may enjoy is "Where Butterflies Grow" by Joanne Ryder and Lynne Cherry.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. All information given in this column is based on university research. To ask a question, call the Master Gardener Help Line at 218-454-GROW (4769) and leave a recorded message. A Master Gardener will return your call.