Texas Garden Weed: Annoying Nutgrass

Southern nutgrass (Cyperus rotundus) is one of the most troublesome species in the area and is the one discussed here. A mature plant of this species consists of a seed stalk, foliage, a crown, rhizomes, tubers and roots. Seed is produced abundantly but their viability is low. Rhizomes grow from the crown of the nutgrass plant and form tubers in a chainlike fashion. A well developed chain may consist of 15 or more tubers and each develops six or more buds from which sprouts can emerge.

Tuber Control

Tubers are the most common means of propagation and most control methods are directed toward their destruction. A cubic foot of heavily contaminated soil may contain 1,500 or more tubers. Height, light, temperature and soil moisture are some of the factors affecting the propagation of tubers. Sprouting of tubers in the same chain and buds on the same tuber usually is progressive.

Destruction of the tuber and breaking the chain between tutors stimulates re-sprouting. Although tubers dry slowly, tillage that detaches and brings them to the surface is the most practical method of control. The killing of nutgrass is not an easy matter and persistent effort is required for its complete control. The object to keep in mind at all times is to keep down the aboveground part of this weed during as large a part of the growing season as possible. This causes the roots to become exhausted.

What To Use

Contact and residual oil sprays, systemic herbicides, fumigants, soil sterilants and mixtures of various herbicides are used alone and to supplement other practices for control of nutgrass. A wetting agent should be used with most chemicals at the rate of one teaspoon liquid material or three tablespoons of dry material per gallon of chemical and water mixture. Apply oil sprays to the crowns of nutgrass or saturate the foliage. Apply other sprays to the foliage or to the soil or to both.

When To Apply

According to research, herbicides control nutgrass best when they are applied several weeks before dormant tubers are formed and applied at within four weeks after nutgrass emerges during the spring. However, control measures are effective any time the grass is growing. Herbicides used for control of nutgrass must be kept off plants and should be applied when the temperature is above 60 degrees Fahrenheit. Those with residual effects must be kept from the feeding range of roots of nearby plantings.

Soil fumigants are for use prior to making new plantings in a new area and soil sterilants should be used only in an area remote from plantings. Several chemical treatments are effective in nutgrass control when used according to the manufacturer's directions printed on the label.

http://en.wikipedia.org/wiki/Cyperus_rotundus