HEAVY FROSTS ON THE WAY. Frost is an interesting process that occurs on clear cold nights when turfgrass plants reradiate heat (exothermic reaction). As this heat is lost to the atmosphere the plant leaf cools, and if the plant temperature is cooler than the air temperature moisture from the atmosphere will condense on the leaf. If the leaf temperature is below freezing then the water freezes and frost forms. Frost will occur even if the air temperatures are slightly above freezing. At this time of the year it is not uncommon to have frost form even if the air temperature is in the mid to high 30's.
Frost does not form as readily on cloudy nights because the clouds reflect, or absorb and then reradiate the energy back towards the turf. Thus, the plants receive heat from this rerediation. Frost also does not form as readily under conditions where a breeze is present. Through convection the mixing air closest to the plant and the atmosphere buffers the leaf temperature drop (also promotes evaporation of the water droplets from the leaf). Areas with little slope have a greater potential for frost than sloping areas (air moves downward resulting in a mixing).
Frost will normally form early in the morning before sunrise. This makes sense because if the plants have been reradiating energy throughout the night, the leaf temperature should be the coolest prior to daybreak. Actually frost may continue to form briefly even at daybreak due to the low angles of light coming from the sun may not directly hit the leaf.
Most damage caused by frost is due to traffic and generally superficial. This is not to say that traffic should be allowed on frosted turf. If traffic occurs, weather it is foot or mechanical, damage caused by “crushing” the leaf blade will occur. Recovery will occur once new leaves are generated.
SPRING-BLOOMING BULBS. Spring-blooming bulbs, used in the northern United States, can be planted now. In the northern United States planting bulbs in September may result in flowering during November if temperatures are ideal The most popular bulbs to plant include daffodil, hyacinth, lilies, and tulips. Bulbs planted in mass will have the strongest visual impact on the landscape. When selecting bulbs choose bulbs that are firm, and solid to the grasp. Also, larger bubs tend to produce larger flowers.
GRUB DAMAGE. Grub damage is quite apparent in many areas of the United States. A good sign that grubs are present, is the digging up of the turf by raccoons, skunks and in the south by armadillos. Generally areas that are more heat and drought stressed will often show grub symptoms. These areas are often in full sun, and have a south-facing slope. Turf that is well-drained, moist, and have high organic matter are especially susceptible.
Grub damage is easily determined by pulling back the sod. If the turf pulls back easily as if to lift pieces of sod, this is often grub damage. Grubs feed on the roots at the thatch/soil interface, which results in the turf being easily “peeled back”. Often times the grubs will be present where the sod has been removed. If the soil is dry, digging down a short distance may reveal the grubs.
Grub damage occurs primarily in the north on Kentucky bluegrass and fine fescue turf. It can also occur on the other cool season turfgrasses including the endophytic containing perennial ryegrasses.
SOIL TEMPERATURES.
|
|
