Lawns

It is that time of year that I encounter a number of individuals who either call or come to the office who have questions regarding their lawn.  One of those questions has to do with timing of fertilizer application. The rule of thumb that seems to work is that when you have mowed 2-3 times it is time to fertilize.  Due to a cooler or milder spring and irregular weather we experienced this spring the growth of most of our turf grasses has been slowed considerably.  Understand, that I mean turf grasses not the winter rye grass and rescue grass we see growing like wild.  Unfortunately, we can’t do anything for those now; but, the good news is the heat is here and they will soon go away. If you are having to mow, that indicates the turf is actively growing and is therefore ready for that first application, preferably I would encourage you to take a soil sample to see exactly what your lawn needs, if not, products with a 3-1-2 or 4-1-2 ratio would most likely to a good job.  Apply at a rate of 1 pound per 1000 square feet of turf.  The weed and feed products that are so popular are not a good idea since your weed control should have been applied weeks ago.  If you are having major weed problems give me a call or bring in a sample and we’ll come up with a plan for your yard. 

Another question that comes up regularly is concerning dead areas in the turf.  There can be many causes of dead spots.  One question you need to answer is, can these dead spots be lifted by hand and or rolled up like carpet.  If so, your lawn may have been damaged by white grubs.  White grubs are simply the larval stage of the May or June beetle.  These root-feeding grubs are creamy-white and c-shaped with three pairs of legs, and their damage normally occurs during the summer and early fall.  They feed on grass roots and the damaged areas begin to show up as weakened or dying grass in irregular shapes.  Eventually, if the population and damage is severe, these areas will die.  To locate grubs, dig with a spade or shovel to a depth of at least 4 inches.  Finding 3-5 grubs per square spot suggests an insecticide treatment is needed.  Apply control in June or July and use a product that contains imidacloprid, halofenozide, trichlorfon or carbaryl.  Be sure to read and follow label directions.  For those interested in non-chemical control, beneficial nematodes can be purchased in garden centers or through garden supply catalogs.  Research shows that under good conditions, commercially-available nematodes can reduce white grub populations by up to 50 per cent.  There are several good products available locally.  If you would like a list of grub control products call or come by the Extension office or visit the Aggie-Turf website at http://aggie-turf.tamu.edu.

Weed Control in Turf

            In lawns and sports fields, weeds are often the result of poor quality turf, rather than the cause of poor turf.  The aggressive nature of weeds and their prolific reproductive capacity enable them to invade thin, weak turf areas.  Cultural practices should always be viewed as the first step to effective weed control.  Always determine why weeds established a foothold and correct those deficiencies.  If the basic problem is not corrected, weeds will continue to occur.  An effective weed-control program also requires identification of the undesirable species as to its classification as a grassy weed, a broadleaf weed, an annual, or a perennial.  Most turf weeds belong to two principal categories – grasses and broadleaf plants.  Chemical controls for these two categories of plants frequently differ. 

            Grassy weeds have jointed, hollow stems; leaf blades have veins parallel to leaf margins, and are several times longer than they are wide; roots are fibrous and multi-branching; and flowers are usually inconspicuous.  In contrast, broadleaved plants often have showy flowers; leaves have a network of veins at diverse angles to one another; stems are often pithy; and a taproot is usually present.  Another group of turf weeds, sedges, have grasslike characteristics, but require a different group of chemicals for control.  Sedges are characterized by three-sided stems (triangular cross-section) which bear leaves in three directions (in contrast to the two-ranked arrangement of grass leaves).

            Weeds can be further grouped according to their life span – annual or perennial.   From the standpoint of chemical control, the grouping is most important, because pre-emergent herbicides are only effective for control of annual weeds.  Annual weeds germinate from seed each year, mature in one growing season, and die in less than 12 months.  Crabgrass and henbit are examples of annual weeds – crabgrass being a summer annual and henbit being a winter annual.  Pre-emergent herbicides must be applied according to the expected date of emergence for each targeted species. 

            Perennial weeds live more than one year, and recover or regrow from dormant stolons, rhizomes, or tubers as well as from seed.  Control of perennial weeds requires a post-emergent herbicide during its season of active growth.  Products such as Portrait, Amaze and Dimension are available locally and need watering in order to activate.  

            Effective chemical weed control requires identification of the weeds as to their Classification (grass, broadleaf, sedge, etc.), life span (annual or perennial), and season of active growth (cool season or warm season).  Effective chemical control also requires accurate timing of applications, proper rate of application, and uniformity of application.  Always follow label directions for a product, and observe all warnings and precautions relative to safety of the application.  Herbicide labels should be carefully reviewed for additional details on specific uses of each product.