With the winds, cold temperatures and natures timing, leaves are falling at great numbers than we can remove. The staff are out trying to clean off greens and our bunkers today. I know they will not get finished since we had to delay our start because of frozen turf grass. Tomorrow, we will begin to clean off fairways and move material into the rough areas. We will be utilizing 2 blowers, the vacuum, at least one rough mower for mulching and probably at least one or two guys doing greens and finishing bunkers. We attempt to grind up as many leaves as possible which do provide some nutrition and soil tilth. Too many leaves ground up in one area can smother grass, change pH of the soil and create additional layering for our grass which can restrict growth. This is why we use our vacuum to pick up and remove large quantities of leaves.
Once the leaf work does slow down, we will begin to pull plugs in the rough to improve water penetration and turf health. This will help to increase freezing and thawing cycles within the turf which leads to the soil becoming more fractured. The heaving of the soil improves exchanges of gases and root development in the soil profile. We plan to pull cores in the rough until the ground freezes and in late winter/early spring when turf thaws. This will strengthen our plants for the summer heat by improving moisture movement through the soil profile and at the same time allow for moisture retention due to millions of small water holding holes in the soil. The more water that can move into the soil, the deeper it can move which will strengthen the plant through improved root systems. As in trees, the more branching of a root system, the greater the water/mineral uptake and the more production of energy which then leads to more growth. Excess energy is then stored within the plant. This storage becomes most important in the heat of the summer when plants naturally protect themselves from the heat by slowing their growth. When you slow production, less is available for the plant to survive. The larger reserves, the better chance and plant has to survive stresses such as heat, disease, insects, mowing, walking, golf carts or having a divot removed..
Allow me to shift gears for a couple of paragraphs since we are talking trees. Most superintendents are not judged on how they can grow a tree. Warning, editor opinion. (Pretty easy, plant to grow, keep mowers off of it and watch it dominate its landscape unless a disease and or pest takes it out. In most cases, they are pretty bullet proof) Superintendents are judged primarily on how we can grow turf grass, specifically golf greens. In a nutshell, that is why I'm so concerned about the competition created between trees and grass. During ideal summers when there is reasonable amounts of moisture and milder temperatures, heavily shaded poa annua infested greens are not much of an issue. Poa annua is a nice rolling surface except for the seed head disruption in the spring. Its when we have a horrible summer like 2011 with high temperatures, high humidity from heavy rains and saturated soils when our turf suffers the most. The plants have not been able to store as much energy as they should because of shading and or competition from tree roots. Green root systems are less branched and become lazy because of excessive moisture from poorly draining and slow to dry shaded turf which means less food production is occurring during the build up to the summer.
Its then on like Donkey Kong. High heat increases soil temperatures. Water is a great conductor of heat and with heavier rainfall, the green profile does not release the heat like it should. As soil temperatures increase into the upper 80's and then 90's, the plants begin to lose root structure. Cells begin to die one at a time as do the root that is made up of these cells. We talk about roots shortening which does naturally occur during an average summer but can be exacerbated due to compromised and unhealthy environments leading up to the severe weather conditions. The higher the temperature, the more severe the impact on the plants. Poa annua root systems already shorter by biology then bent grass, suffer more severely because of this shorter root system. More water is necessary to keep it cool but then their is too much water for the bent grass plants. Bent grass, normally the stronger plant is weakened, has fewer numbers because of competition from the poa annua and poor growing conditions.
In most cases, poa annua will colonize greens in certain areas. High moisture concentrations and shade are the two biggest factors. The higher areas of concentration of this weaker plant species, the greater potential for larger areas of damage due to heat, excessive moisture and or disease. Less root structure means less water/mineral intake. The plant then overheats because it cannot cool itself. In a way like humans, the plant basically goes through heat stroke and or exhaustion. The plants systems begin to shutdown one at a time until it finally dies. Root diseases can also begin to show their ugly head. This type of stress require chemical applications which are generally very expensive and require the highest labeled rates to apply and usually more than one treatment. These applications can negatively affect the microbial populations which help to breakdown nutrient products and make them more readily available for the root systems to move into the plant. At a time when the plant might need to be stimulated, this process slowed because of reductions in the life within the soil.
Golf greens are made up of about 2000 plants per square foot. Below is a hypothetical example.
4000 sq foot green 5% turf loss = 200 sq feet of total turf loss
200 sq feet of turf loss x 2000 plants = 400,000 plants.
In most cases when areas begin to die or suffer, the leaf or leaves from one plant only die back to the crown where new leaves will regenerate. If the weather changes for the better, damaged areas can heal fairly quickly. If weather severity continues, the damage can continue to spread. Sometimes, damaged areas require changes in maintenance practices to encourage healing which includes reducing mowing schedules and or raise the height of cut which can negatively effect ball roll. When death does occur, that's when we have to seed into areas and or replace the damage through plugging and or sodding. Okay, enough proselytizing for one session. Need to go out and help the staff remove leaves!!