To mulch or not to mulch When should you stop putting mulch around trees? We heard that the tree roots will remain near the surface and not penetrate the soil when mulch is used. - Michigan

Increased air exchange, soil porosity and increased water absorption and retention are all benefits provided by mulch that promote and encourage root growth. However, if poor soil conditions exist, roots may favor the environment created by mulch and not penetrate the surrounding soil. This may cause roots to become exposed and possibly damaged from mechanical operations. Also, more roots near the surface can promote drought stress during hot periods with little rainfall. In heavy clay soils that discourage root growth, these effects are more pronounced. Regardless, the tree is better off with the mulch and its positive benefits than without it. If the roots prefer to grow in the mulch rather than the soil, it is an indication of poor soil characteristics or poor planting procedures.

To mitigate these effects, it is important to properly plant trees and shrubs. You must dig a large enough hole and use a non-compacted soil when backfilling the hole to encourage root growth in the soil and not above it. During hot, dry periods, water deeply to encourage root growth in the soil. Instead of applying 1 inch of water four times a week, try watering once a week with 4 inches of water so that it will penetrate deeper into the soil.

When do you stop applying mulch? On larger trees or in areas where mulch does not serve any aesthetic purposes, mulch use can be discontinued. However, it will still provide many benefits to the tree. If possible, you should continue mulching.

One of the greatest benefits of mulch is weed suppression. Therefore, if you discontinue mulching, be sure that string trimmers or other equipment does not damage the trunk when removing weeds and grasses.

Sealing gaskets What is the difference between the types of gasket sealers? What's most suitable for mowers? - via the internet

According to Robert Sokol, editor of the Clymer Power Sports Bluebook, gasket sealers fall into three categories. The first and most popular choice is silicon. But be careful. Many people figure that if a little sealer is good, more must be better. This is wrong! Use only a thin layer of silicon. Using a thick layer can cause excess silicon to come loose in the engine and cause problems.

Do not use silicon on head gaskets. According to Sokol, the rule of thumb on head gaskets is to follow the factory shop manual on sealers if you are using an OEM (original equipment manufacturers) gasket. If you are using an after-market gasket, follow the recommendation of the manufacturer.

Gasket shellac is another type of product. It is not a sealer but rather more like a glue. It should be used only where there is little to no pressure, such as a gasket placed between an engine and a mower deck. It is very cheap and will hold (glue) the gasket in place so that you can place the components together without the gasket moving.

All three types of categories have uses on mowers; it depends on which type of gaskets you are working. Again, always follow manufacturers' directions when they are provided.

Reseeding divots We would like to treat our golf tees with a pre-emergent herbicide to control crabgrass, but we are worried that, if we did, we wouldn't be able to reseed divots. - via the internet

I consulted with Dr. Jack Fry, professor of turfgrass management at Kansas State University. He said your ability to reseed would probably depend upon the depth of the divot. "Most pre-emergence herbicides are not mobile in the soil and would remain near the soil surface. Removal of a divot should remove the herbicide from that area, and it is unlikely that herbicide from the surrounding area would translocate into the seeded area. Therefore, the addition of a sand-seed mix into this area should result in good germination and establishment. That said, a shallow divot (one that removes more turf than soil) may have enough herbicide remaining at the surface to inhibit growth of new seedlings."

The use of activated charcoal may prove beneficial. Commonly used to clean up spills, activated charcoal is also used for deactivating pre-emergence herbicides when reseeding. Mix 1 to 2 pounds of powdered activated charcoal with 1 gallon of water and apply it as a slurry so that the charcoal can penetrate the thatch layer and be incorporated with the herbicide. Also, if the herbicide is watered-in beyond the thatch layer, rake the slurry into the soil. If charcoal is properly applied, the soil can be reseeded 24 hours after treatment.

High energy prices are affecting the green industry by directly increasing the operating costs of equipment. Everyone is feeling these increases and there appears to be no relief as we head into the 2001 season. But, the industry also faces another threat from energy costs: The cost of fertilizer production is increasing with the costs of natural gas.

Petroleum prices have found some stable ground, albeit high ground, this fall and winter. However, fertilizer production depends on natural gas and The Fertilizer Institute (Washington, D.C.) reports natural gas prices increased from $2.50 per million Btu in January 2000 to over $10 per million Btu last month.

While natural gas is used to produce many fertilizers, most of it used in fertilizer production is used to produce nitrogen-containing ammonia. At 33.5 million Btu to produce 1 ton of ammonia, the quadrupling of gas prices last year has caused natural gas to account for a whopping 92 percent of the cost to produce 1 ton of ammonia. The increased production costs are forcing U.S. producers to choose between selling at a price below the market price or curtailling production. Meanwhile, producers in other countries where natural gas is still cheap are expanding production and increasing exports to the U.S.

At this point, agriculture is at the greatest risk while the effect on the turf and ornamental market is unclear. Unlike agriculture, the turf and ornamental market often reformulates raw ammonium products. Therefore, reformulated supplies currently available may have been manufactured several months ago before the recent spike in gas prices. However, there's a good chance we will experience some price increases as the green season goes into full swing in the next few months.

When is the best time to seed grasses? This question is asked frequently, but there has been little actual research to support the early fall and dormant seeding that is frequently practiced for cool-season grass establishment. Researchers Zachary J. Reichart and Clark S. Throssell and professional agronomist Daniel Weisenberger tested Kentucky bluegrass, perennial ryegrass and tall fescue to determine establishment, survival and ground coverage after seeding and throughout the following growing season.

The researchers seeded plots with Kentucky bluegrass, perennial ryegrass and tall fescue on Sept. 1, Oct. 1, Nov. 1, Dec. 1, March 1, April 1 and May 1 in years 1989-1990 and 1990-1991. The plots were irrigated to facilitate germination and establishment.

Their results confirm that early fall turf establishment (Sept. 1) offers good coverage by December. However, perennial ryegrass and tall fescue cultivars achieved better coverage than the slower-germinating Kentucky bluegrass cultivar. Also, Sept. 1-seeded swards had significantly greater coverage during the early sampling period (May) of the following year than swards seeded at any other date. However, coverage differences between seeding dates became less significant by the latter part of the growing season (July and August). By this time, the later-seeded swards had become established.

Quick-germinating perennial ryegrass seeded in the late fall (Nov. 1) performed poorly during spring and early summer, and coverage was significantly worse than the other species throughout the entire year. This was attributed to late-season germination and subsequent winterkill of the new plants. Winterkill did affect Nov. 1-seeded tall fescue and Kentucky bluegrass, but to a lesser extent because fewer seeds germinated prior to the onset of cold winter conditions.

The researchers also note that summer weather conditions greatly affected the percent coverage and the ability of grasses to compete with crabgrass emergence. Early seeded (Sept. 1 and Oct. 1) swards have consistently greater coverage and less crabgrass invasion by August of the following year than swards seeded at any other time of the year. Also, dormant-seeded swards of all species performed well during the following summer and provided coverage that was rivaled only by Sept. 1 seedings.

Early fall and dormant seeding has been the norm for turf establishment in the Transition Zone. The quick germination of perennial ryegrass does limit its suitability for late-fall or early-dormant seeding, but it is suitable for seeding dates into early October (depending on your location).

Seeding is a race against the weather. Early fall seedings typically provide a cool growing season in the fall to germinate and become established. This is followed by another cool growing season in the spring before hot summer temperatures arrive. Dormant-seeded grasses have the advantage of germinating as soon as weather permits in the spring and taking advantage of all of the cool spring growing season. By contrast, spring-seeded grasses have little time for establishment before weather becomes hot.

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