Landscape and nursery
§ Late summer spider mites or aphid problems may appear where insecticides were used earlier
§ Fall webworms make a good classroom demonstration
§ About hosta virus X
§
Emerald ash borer treatment tour – Sept. 8 in
Turfgrass
§ Turf recovering
I have seen this happen many times at professionally managed landscapes and at my own home. I remember a few years ago I sprayed one outside corner of my garage for carpenter ants in May. In July I was shocked to see that the spirea growing against the garage where I sprayed was covered in aphids. In the five years before that, and for several years after, it never had aphids. The pyrethroids insecticide I used for the ants had knocked-out the natural predators and parasites of the aphids, causing a local outbreak.
This summer I have done it again. I had a problem earlier in
June with some caterpillar feeding injury to my bee balm. I sprayed the bee
balm with a pyrethroid insecticide, not realizing that I was also spraying the
impatients in front of them. Two weeks ago I noticed that half of my bed of
impatiens had dropped most of their leaves. When I examined them closely, I
found hundreds of spider mites on each plant. The damage could easily have been
mistaken for a disease problem because the impatiens dropped their leaves so
quickly from the mite injury. I am including some pictures of the mite injury
to the impatiens because we have had some phone calls from people in the
Everybody is complaining about those nasty looking webs on the walnut and hickory branch tips. They don't usually harm the trees in any way, but they just look bad. Pruning them out is the only way to get rid of the unsightly tents. But when you remove the tents, try a little experiment.
Put one of the tents or part of a tent in a gallon-size zip-lock bag and keep it in your home at room temperature. Add fresh leaves from the same tree every other day to provide food for the caterpillars. Keep feeding the caterpillars for 1 to 3 weeks until they have all made cocoons. Then the magic will happen. Some little (1/8 - 1/4 inch long) wasps will start to appear inside the bag, maybe 3 or 4 different kinds, and perhaps even a hundred of them! These are the natural parasites that lay their eggs inside the webworm caterpillars. The wasp larvae feed inside the caterpillars, devouring them, pupating, and turning into the little wasps you see inside the zip-lock bag. They are harmless to people. Release them outside when you are done. These little wasps will help bring the webworm outbreak under control next year or the year after.
At the nursery summer tour on Thursday, August 25, there was
considerable interest in Hosta virus X (HVX). The virus is from the group
potexvirus and is the most commonly occurring virus of hostas (Hosta spp.) in the
1) Susceptible to infection, with symptoms of varying degrees of severity;
2) Susceptible but showing no visual symptoms (tolerant); and
3) Immune to infection with no symptoms.
Dr. Lockhart of the
Table 1 Reaction of
57 hosta cultivars, varieties and species to natural or experimental infection
by hosta virus X (HVX). (From
Lockhart Proc. 10th IS Virus Diseases Ornamentals; Ed. J. Hammond, Acta Hort.
568, ISHS 2002)
|
Reaction type |
||
|
Susceptible |
Tolerant |
Immune |
|
Birchwood Parky’s Gold Yellow Splash Rim Hydon Sunset Rim Rock Janet Kara Lunacy Honeybells Moonlight Sport Gold Edger Golden Prayers Golden Tiara Color Glory Golden Medallion Fragrant Gold Emerald Tiara Royal Standard Crown Prince H. clausa normalis H. opipara (Benedict)
H. lancifolia H. decorata H. undulata H. fortunei
hyacinthina H. ventricosa H. |
Blue Wedgewood Green Fountain Halcyon Harvest Glow Northern Exposure Northern Halo Shade Fanfare Sun Power Sweetie Ryan’s Big One H. siedoldiana elegans H. ventricosa aureo- marginata |
August Moon Frances William Fragrant Blue Gold Standard Hadspen Blue Holly’s Honey Invincible Love Pat Regal Splendor Solar Flare So Sweet Sum and Substance Wide Brim H. fluctuans
variegata H. montana aureo-
marginata H. pulchella
kikifurin H. subcrocea H. tokudama aureo- nebulosa H. tokudama flavocircinalis |
It is not possible to cure a plant of viruses. A virus-free plant might contain an unknown virus and therefore it is more correct to call them virus-tested or virus indexed plants. For example, production of virus tested seed stocks in other crops such as potatoes is started using thermotherapy; treating apical meristematic regions of plants with temperatures of about 35oC for up to 20 weeks then planting the surviving heat treated buds into sterile sand. This is based on the principle that often the terminal buds of plants are free of virus. Other virus tested procedures involve removal of the bud tip (0.03 to 0.05 mm) and growing it in sterile agar containing nutrients, e.g. for tissue culture. Although most of the buds will die some will grow and develop into mature plants. These plants should be subjected to a virus-screen and virus-tested plants can then be used to initiate a virus-indexed population. The virus indexed plants should be propagated under sterile conditions at a low temperature to minimize growth and development. Scions from the microplants can then be used to generate plants for field propagation.
Join Michigan State University, Michigan Green Industry Association, and others from the industry in this tour of emerald ash borer (EAB) treatment successes and failures. Tour instructors include MSU entomologist Dave Smitley and Extension specialist Dave Roberts. The tour will feature MSU research from the past two years into EAB treatment and control. Industry professionals will also lead stops at sites where their research indicates the success of various treatment methods for controlling EAB. The tour ends at Firefighters Park for questions and answers about controlling EAB outside of the quarantine regions. Tour discussions will include procedure methods, application techniques and environmental concerns related to applications.
Host: Michigan Green Industry Association
Date: September 8
Time: 12:30 PM – 5:00 PM
Start location: Firefighters Park, 1800 W. Square Lk. Rd., Troy, MI
Cost: MGIA members, $40, non-members, $55.
The following credits have been approved: 2 MDA pesticide commercial core or private core and 2 – 3B or 6 ISA – 4, GCSAA - .35.
Pre-registration is required. Call MGIA at 248-646-4992.
The summer of 2005 will be remembered as one of those years when turf struggled and turf managers developed ulcers. The high humidity, high temperatures, and depending on location either drought or gully washers from thunderstorms, resulted in quite simply, plenty of dead turf and of course lots and lots of pretty crabgrass. Turf managers understand that sometimes turf just dies, if the turf you managed hasn’t died yet, just wait sooner or later it probably will. However, for homeowners losing turf can be a traumatic experience that often leaves them scratching their head trying to figure out why they can’t quite keep up with Mr. Jones down the street. I have talked several homeowners off the ledge during the summer but the good news is that fall is coming quickly. Below are several turf saving tips that will hopefully help the turf recover from this dastardly summer. Of course, we still need some rain!
Labor Day is one of the holidays that comprise the “Holiday” fertilization calendar. Fertilizing turf around the Labor Day holiday will help the turf recover from summer stress. A September fertilizer application will help by stimulating tillering and rhizome growth (lateral spread of turf) which help the turf fill in bare areas.
Many soils that we grow turf on in urban areas are far from ideal and one of the simplest and most effective ways to improve soil and turf conditions is through core aeration. Core aeration is effective because it opens up or aerates the soil. The core holes provide oxygen to the root system and will facilitate rooting depth, especially in heavily compacted or high clay content soils. Soil moisture or lack there of, may make core aeration difficult this fall. If soil moisture is adequate or you irrigate, it won’t be a problem but on drought stressed (read brown turf) sites you might want to hold off. Coring drought stressed sites may actually do more damage than good because the turf is already stressed and won’t be able to recover as quickly.
You can hire a local landscape/lawn care operator to core aerate the lawn for you or you might be able to rent a machine from the local rental store. Caution, if you have an in-ground irrigation system make sure to identify the location of all the sprinkler heads and be confident in the depth of the pipe before you begin poking holes. Also, for those with an Invisible Fence for dogs – you might want to stay away from that border to make sure you don’t punch through Spot’s containment wire.
Granted homeowners are inclined to embellish, but not too long ago I had a call that really put a smile on my face. The homeowner called and was very concerned that a “large orange growth” seemed to be spreading through the lawn and would quite likely take over the entire neighborhood. What was it and what should be done?
Clearly the homeowner had a bad case of Rustus Phobias, a common homeowner malady this time of year when the turf is a little dry, isn’t growing all that vigorously, and the new school sneakers return from the lawn with a new orange hue. Rust is an annual problem in turf in Michigan, some years it’s just worst than others and this fall might be setting up to be one of those big rust years. If your lawn appears yellowish from a distance and upon closer inspection of leaf blades reveals yellow or dark brown or iron/rust colored spores, you’ve got rust. The good news is that in all but the most severe cases simply keeping up on your mowing and applying fertilizer should stimulate the turf to outgrow the rust and return your lawn to the green oasis you want, and of course eliminate the rust blob.