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In The Backyard

Horticulture columns and tips done on a timely basis

July 23, 2008

Green June Bugs

Well not a week has passed, and an insect similar in appearance to the Japanese beetle has made its annual appearance. No, you don't have Japanese beetles that have supersized themselves. That insect is the Green June Bug. These beetles are much larger than either June bugs or Japanese beetles. Most people are concerned that they have bumble bees because of the buzzing sound the beetles make when flying.

Green June Bugs are also called fig eaters. This is because they can eat soft fleshed fruits such as grapes, plums, peaches, and apricots. In their larval stage they are a grub, but don't do a lot of turf damage like the normal June bug. They tend to be in high organic matter places such as flower beds, gardens, compost piles, and under shrubs.

As for control, there is probably none necessary unless you need to protect those soft fleshed fruits. Then you should follow the recommended spray program so you don't cause problems with the fruit later on. The Green June Bug doesn't sting or bite, so you can put them in the nuisance pest category. The main damage they can do is fly into you, and that can hurt. On the bright side, you are probably already protecting things of value from the Japanese beetles, so you may be covered.

Posted by John Fulton at 2:29 PM | Permalink |

July 23, 2008

Cicada Killer Wasps

The cicada killer wasps have returned! They are actually considered beneficial insects because they control cicadas. This wasp gets its common name due to the fact that it hunts and supplies its nest chambers with a cicada, which becomes a food source for the young cicada killer. Cicada killers are a nuisance pest, especially when nesting in large numbers in a play area or near the house. People get concerned because the cicada killers resemble giant yellowjackets.

Cicada killers are about 2 inches long and black to red, with yellow banded markings on the abdomen. The head and transparent wings are reddish brown. They are not dangerous, but they are intimidating. Cicada killers are solitary wasps, with the female digging a 6- to 10-inch burrow (1/2 inch in diameter) in the ground. A pile of soil typically surrounds the entrance. The female locates and stings a large insect such as a cicada or katydid and then brings it back to the burrow. She places the insect into a chamber and lays an egg on it; sometimes she puts two in a burrow but lays an egg on only one. She then covers the burrow, digs another, and repeats the process. The egg hatches into a grublike, legless larva that consumes the paralyzed insect. Full-grown larvae overwinter in the burrow, pupate in the spring, and emerge as an adult during the summer, usually in July and August.

Cicada killers are unlikely to sting a person. Wasp and bee stingers are modified egg-laying devices (ovipositors), so males are not able to sting. Females may sting if crushed, either by being stepped on with bare feet or grabbed with bare hands.

Cicada killers are more common in areas with bare soil, so mulching, planting ground covers, or putting down sod can reduce problems. Applying permethrin or Sevin (some suggest the Sevin dust gives better control) to the burrowed area should kill females in high traffic areas. Once females are gone, males leave. In home yards, sandboxes can be covered with a tarp when not in use, as this deters the wasps (and also keep cats out). Sand below swings, jungle gyms, or other playground equipment is a popular site for the cicada killer. Raking the sand may discourage the wasps, or you could use mulch instead of the sand. In extreme nuisance situations, treatment of burrowing areas with a pyrethroid insecticide or carbaryl may reduce problems.

Posted by John Fulton at 2:29 PM | Permalink |

July 15, 2008

Water Damage

Most of Illinois has experienced excessive rains, which have resulted in waterlogged soils and flooding. Logan County has certainly been no exception, with another round of four inches or more common. It is important to understand what is happening to plants growing in these conditions, and what to expect later. It is a wait-and-see situation. Many herbaceous plants are experiencing injury symptoms now. Visible injury symptoms on trees and shrubs may not occur for a year or more. Following is a discussion about flooded and water soaked plants, based on an article done by Rhonda Ferree several years ago.

Injury symptoms, which vary according to several factors, include decreased growth of shoots and roots, decreased transpiration rate, yellowing leaves, twisting of leaves, leaf drop, death of roots, increased susceptibility to attack by predators and pathogens, absence of fruiting, and death.

The main reason injury occurs is related to oxygen availability in the soil. In flooded or waterlogged soils, oxygen diffuses slowly and reduces in concentration to a few percent or zero. As oxygen is excluded from roots, there is decreased aerobic root respiration, root growth, transpiration, and translocation.

Although survival is directly related to species' tolerance of waterlogged soils, other factors are important—including the soil type; the time, duration, and depth of the water; the state of the floodwater; and the age and size of woody plants.

Tolerant species, such as baldcypress, littleleaf linden, redtwig dogwood, mulberry, silver maple, and willow, can live on sites in which the soil is saturated for indefinite periods during the growing season.

Moderately tolerant species, such as green ash, hawthorns, honey locust, pin oak, red maple, river birch, sweetgum, and sycamore, can stand saturated soil for a few weeks to several months during the growing season, but these species die if waterlogging persists or reoccurs for several consecutive years.

Weakly tolerant species, such as American holly, balsam fir, black walnut, burr oak, catalpa, hackberry, Douglas fir, eastern cottonwood, and red oak, can stand relatively short periods of soil saturation—a few days to a few weeks—during the growing season, but they die if waterlogging persists for longer periods.

Intolerant species, such as American beech, black locust, crabapples, eastern hemlock, flowering dogwood, paper birch, pines, redbud, spruces, sugar maple, tuliptree, white oak, and yews, die if they are subjected to short periods of 1 or 2 weeks of soil saturation during the growing season. White pines and burning bushes are among the most sensitive, with saturation for as little as two days can cause root death, followed by plant death.

Unfortunately, little can be done to prevent damage to plants growing in waterlogged soils. If a woody plant shows injury symptoms, such as leaf drop, do not immediately replace it. Some plants will show initial injury symptoms and then recover. Many woody and herbaceous plants, including turf areas, will not recover. Be patient. Whether your plants are simply waterlogged or actually growing in flood areas, it will take a while to see the full extent of plant damage.

Posted by John Fulton at 9:25 AM | Permalink |

July 9, 2008

Tomato Diseases

It seems like the tomato is the one plant that just about everybody tries to grow. Some people grow large amounts, while others plant one or two in containers. At any rate, the calls and samples have started coming in to the office already. Most of the samples have spots, brown leaves, and dropping leaves, or all of the above. Several diseases hit tomatoes, but two of the more common ones are early blight and seporia leaf spot. Blossom end rot seems to have been running rampant on early tomatoes as well.

Early blight, also know as Alternaria leaf spot, can affect plants at any stage of development. All above ground parts are susceptible. The most characteristic symptom of early blight are spreading spots, ¼ to ½ inch in diameter that form on lower or older leaves. These spots have dark edges and they are usually brown to black in the center. These spots frequently merge forming irregular blotches. Concentric rings often form creating a 'target' or 'bulls-eye' effect. Affected leaves develop yellow areas around the lesions. Spotted leaves soon turn yellow, whither and drop off. The fungus may cause lesions on the fruit around the stem end and shoulder. The lesion is usually dark brown to black, up to an inch in diameter, and with distinct concentric rings.

Septoria leaf spot can also affect plants at any stage of development. Numerous small, water-soaked spots first appear on the lower leaves. These spots soon become circular to angular with dark margins and grayish centers often bearing one or more tiny black bodies called pycnidia which are spore-bearing structures. Individual lesions are seldom more than ⅛ inch in diameter and are usually quite numerous on an infected leaf. Heavily diseased leaves turn yellow, wither and drop off in large numbers, starting at the base of the plant. Defoliation can be severe during prolonged periods of warm, wet weather.

As for what to do, here is the checklist: First, keep ripe fruits picked off the plants. Second, don't work around tomatoes when they are wet. Next, you can try and improve air circulation, but if your tomatoes are severely affected you won't want to lose any more leaves. And the final step for this year is to try a fungicide. Mancozeb is probably the recommended one, but it is very hard to find. The other options are Daconil and maneb, which are easier to find but probably won't give you as good of control. The final step for future years is to practice at least a three year rotation, with good sanitation in the garden.

Blossom end rot is a non-pathogenic disease that is very common during extended dry periods. It begins as light tan water-soaked lesion on the blossom end of the fruit. The lesions enlarge and turn black and leathery. This can drastically lower the yield and lower marketability of the fruits. Fluctuating soil moisture supply during the dry periods, and low calcium levels in the fruit are the major causal factors. Control of blossom end rot consists of providing adequate moisture from fruit formation to maturity, and use of mulch (grass clippings, plastic, straw, shredded newspapers, or plastic) to conserve moisture. Avoid frequent shallow watering. Water deep and then wait five or more days before watering again. Proper mulching increases the number of days between watering, and evens out the moisture supply.

Posted by John Fulton at 2:19 PM | Permalink |