Turf Renovation in the Fall
Now is the perfect time to carry out turf renovation projects! Soils are warm and friable and there are timely rains to aid seed germination.
In addition to ideal soil and weather conditions in the fall, weeds such as crabgrass (Digitaria) and prostrate knotweed (Polygonum aviculare) will soon be dying out and winter annuals like chickweed are not at their prime flush of emergence. On the other hand, annual bluegrass (Poa annua) is a winter annual that germinates when soil temperatures dip below 70°F and this could cause some competition issues on compacted fields that have a history of Poa problems.
Many fields still have some ground cover but need to be overseeded with desirable grass seed. For new renovations where there is bare soil involved, the key is to make sure surface grades are correct before any seeding or sodding takes place. Surface grades and surface smoothness/evenness are far harder to deal with after the fact. This is especially important on baseball infields.
Soil ImprovementIf poor drainage is the main issue, medium-coarse, uniform sand can also be incorporated to improve infiltration rates. To gain the most benefit from sand, it should constitute at least 75% of the soil by weight. This would put the texture of the soil into the loamy sand and sand categories. Even the sandy loam soils, which one might consider to have adequate drainage capabilities, can contain as much as 40% silt and clay. This could create compaction and drainage issues down the line. For some reason, increasing sand content and using sand as a topdressing material is a practice that is not done as often as it should be. Topdressing helps to improve field drainage, smooth out holes and undulations, protect new seeds and dilute thatch. Research has shown that mechanical aeration alone does not improve soil conditions and that it is only when topdressing is added that field conditions can truly be corrected.
Weed Control
Existing, dense weed cover can be be killed by a non-selective herbicide like Glyphosate prior to the seeding or sodding process. Weeds like crabgrass that will die at the end of October may still cause problems during the renovation if they are too thick, so killing them prior to renovation will help. Weed prevention on new renovations can be accomplished with a herbicide like tenacity (mesotrione) that will not affect seed germination and will give protection as both a pre-emergent and post-emergent herbicide. Siduron (tupersan) is a pre-emergent herbicide also safe on new seedings. Read the label for a list of target weeds (for example, Tenacity is not labeled for prostrate knotweed). It would also be helpful to have a pre-emergent herbicide ready for late winter (end of Feb-early March 2012) to prevent weeds that emerge first, namely prostrate knotweed and annual bluegrass.
Seed & Fertilizer
After soil amendment and weed control, the next task is seed and fertilizer application. The golden rule of successful seeding in keeping the seed moist until it germinates (that’s 3-5 days for ryegrass, 7 days for tall fescue and up to 10-20 days for Kentucky bluegrass). It is very important that the seed be in direct contact with the soil seedbed through slit-seeding or by de-thatching prior to broadcast seeding. At the same time that seed is applied, a starter fertilizer containing phosphorus should also be applied. Even on soils that have shown sufficient phosphorus levels during a chemical analysis, having phosphorus on the soil surface with the seed is extremely helpful for seed establishment and seedling growth. After the seed and fertilizer have been applied it all needs to be lightly raked or dragged in and ideally covered with topdressing, a growth blanket, or straw. The cover acts as a protector from heavy rains and soil erosion, cold weather and drying effects of the sun and wind. Many years ago I heard Dr. Dave Minner from Iowa describe this process as “putting the field to bed” and that describes the process perfectly!
Post seeding practices include applying supplemental water if it does not rain. The seed needs to be syringed until green cover is seen. Once the seedlings are actively growing, the watering schedule can be taken back to a maintenance regime of 1-inch water per week. As soon as seedlings are 3-inches tall the turf should be mowed with a rotary mower as much as manpower and budget allows. Every day if possible. Mowing is the most simple, and yet the most important practice for turfgrass establishment, density and health. After 2-3 mowings, gradually bring mowing height down to 1-2.5 inches (depending on field use and management level) and continue to mow as much as possible for the next 6-8 weeks, or until the first frost.
While there is no way to predict long range weather, there should be at least another 6-8 weeks of decent growing weather from this point forward. This allows enough time to do renovation and get several mowings done before the turf goes dormant for winter. The last important task of the growing year will be the late season fertilizer application, made around Thanksgiving.
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