Answers to Garden Questions
Birds feeding in the lawn brings questions about the health of the lawn. Knowing it is grub time may indicate the need for applying an insecticide for control. There are a number of insects along with earthworms that birds feed on. What they are feeding on may or may not be a turf pest. It is important to be familiar with the life cycle of turf grass insect pests to know when a damaging stage of the insect development may be present. If it is the correct time of the year for that specific pest, then it is necessary to determine if the number of insects present is high enough to warrant significant damage. It is not recommended to apply an insecticide for control without confirming the presence of a damaging pest population. White grubs, for example, may be of concern this year through early June. If 5 to 8 grubs can be found per square foot, insecticide may be warranted. Control can be obtained using imidacloprid (Merit) or halofenozide (Mach 2), carefully managing correct irrigation for effectiveness and recovery of the lawn.
Maple bladder galls have reappeared. These galls are the little bladder like growths on the top side of the maple leaves. Actually, they occur from the string of a mite that has crawled up from the bark of the tree trunk to feed. The University of Nebraska still does not recommend control. Though they are unsightly, they will do little damage to the tree. The fact that the mite is already entombed inside the little colorful bladder, it is not going to be affected by an application of insecticide at this time. Leaves covered with these galls will eventually dry up and fall to the ground.
Iron Chlorosis causes trees to turn yellow while the veins remain green. Browning along the leaf edges and between veins and twig dieback are also symptoms. Iron chlorosis is most likely to show in the oak trees, silver and red maple and ornamental pear in the Hastings community. This is due to the high soil ph, or what is called alkaline soils. If iron chlorosis appears in one of your favorite trees, it is suggested to add additional iron, such as iron sulfate, through trunk injections or soil applications of iron. Contact the Extension Office for details, or the possible check-out of equipment for self application of trunk injection.
Hail damaged trees are apparent throughout the area. It is safe to assume that most trees, though stripped of leaves and showing visible trunk and branch damage, will develop secondary leaves. These trees will generally heal, though scars of the hail storms will be visible for years.
Wind damage to tree leaves has resulted in several calls to the Extension Office. Many of the leaves are turning dark brown or black along the edges which look like a burn. Wind whipping through the young tender leaves will tear and brown many leaves. This is not insect damage. There is no reason for concern as the tree will grow additional leaves as the season progresses.
Roses are beautiful this year. With the many species of roses, color seems to show everywhere in the residential sections of town. With this beauty comes a host of rose issues. Rose slugs cause rose plant leaves to become skeletonized and turn brown. Slugs are the larvae of rose sawfly, a small, dark, non-stinging wasp. Black spot of roses causes small black spots on leaves with yellowing and defoliation. Severe defoliation can eventually lead to plant death. Rose rosette is a disease found on multiflora or wild roses and cultivated roses. It is thought to be caused by a virus although not confirmed. Plants infected with rose rosette may show a combination of lead distortion, rapid stem elongation, a mosaic pattern on leaves, and excessive thorn production. Leaf cutter bees on roses are perfectly round holes in the rose leaf or on leaf edges made by leaf cutter bees gathering leaf material for nest making. The holes are harmless to the roses. This bee is a very important pollinator. Do not use insecticides. Rose chafers are scarab veetles about 3/8 inch long, slender, and light tan. Adults feed on rose flowers and foliage. Hand pick where seen.
The season for red spider mites is upon us, especially with the dry weather with few heavy rains. Mites feed by sucking plant juices with piercing-sucking mouth parts, causing white or yellowish specks on leaves, then to bronze discoloration. Control by hosing with a still water stream, or using an insecticide such as Kelthane, malathion, Cygon or Orthene when mites are active. Shaking or tapping a branch over a white piece of paper is the best way to monitor for infestation.
If questions about any of the above, I urge you to go to the computer, type in the name of the plant, right slash, followed by unl.edu. You will surprise yourself with the abundance of information available. I urge you to only select material from a land-grant University source, by staying with those articles that contain the .edu in the source line. Surrounding states within plant Zone 4-5 have a wealth of knowledge applicable to Hastings.
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