How to Manage Pests

UC Pest Management Guidelines

ANNUAL BLUEGRASS. Annual bluegrass is a cool-season grass that germinates when soil temperatures are less than 70° F. It is especially prevalent in wet areas. Several preemergent herbicides will control annual bluegrass. Ethofumesate also will control annual bluegrass after emergence, but it must be applied to very young seedlings. Seed production by this weed can be suppress with a plant growth regulator.

BERMUDAGRASS. Although bermudagrass can be used as a turfgrass, its rapid growth by stolons into other turfgrass areas makes it a weed in those situations. Bermudagrass is a perennial that is commonly found throughout California. It spreads by seed and by stem sections (rhizomes and stolons). The rhizomes and stolons are many jointed and root at the nodes. Bermudagrass does not grow well in the shade. Fall and winter fertilization and high mowing heights (greater than 1.5 inches) will reduce bermudagrass invasion into cool-season turf. Avoid spreading stem sections of bermudagrass to uninfested areas with mowers and other turf maintenance equipment. Preemergent herbicides (pendimethalin, siduron, or benefin plus trifluralin) will aid in the control of germinating bermudagrass seedlings.

CALIFORNIA BURCLOVER AND BLACK MEDIC. California burclover and black medicare annual or short-lived perennial weeds that infest turf. Invasion by these two species is encouraged by low nitrogen fertility. Herbicides that control these annual species include clopyralid, dicamba, mecoprop, quinclorac, or triclopyr.

CRABGRASS. Two species of crabgrass that commonly infest turf in California are smooth crabgrass and large crabgrass. Both species are annuals that spread primarily by seed, and to a lesser extent, by rooting at swollen nodes of stems. Crabgrass is frequently a problem in overirrigated turf. Frequent, shallow irrigation encourages the establishment of crabgrass. Preemergent applications of products containing benefin, bensulide, DCPA, dithiopyr, oryzalin, oxadiazon, pendimethalin, prodiamine, and trifluralin control crabgrass. Siduron can give some control when cool-season grasses are planted in spring. Postemergent applications of products containing MSMA will aid in the control of crabgrass. Quinclorac is useful for large crabgrass control but has given mixed results on smooth crabgrass.

Crabgrass may germinate in warmer parts of the state throughout the year. In southern California, the major germination period is from late January to early March, depending on the weather, and seeds continue to germinate throughout the spring and summer. While germination is early in warm winter areas, growth is slow during spring months until mid-May. In June and July the plants produce tillers, shoots, and flowers in late July and August. Crabgrass may overwinter in warm areas and produce new growth and a second crop of seed in spring or early summer. For best control, apply preemergence herbicides before the end of January in warm winter areas. The optimum application period for postemergence herbicides in these areas in late May.

CREEPING WOODSORREL (Oxalis corniculata). Creeping woodsorrel is a perennial that is often found in well maintained turf areas. Creeping woodsorrel grows year round in California and produces running rootstocks and has leaves similar to those of clover. There are no cultural controls available for this weed. Preemergent treatment with herbicides containing pendimethalin, isoxaben, or dithiopyr will limit emergence. In cool-season turf, postemergent treatment with triclopyr controls creeping woodsorrel. 2,4-D does not control this weed.

DALLISGRASS. Dallisgrass seedlings germinate in spring and summer and it becomes a perennial with the formation of short rhizomes. It has a clumpy growth habit that gives turf an irregular surface unsuitable for most sports activities. Repeated postemergent treatment with MSMA or nonselective spot treatment with glyphosate can reduce dallisgrass infestations. To control seedlings use a preemergent herbicide.

DANDELION. Dandelion is a perennial with a heavy taproot. Removal of the leaves and 1 to 2 inches of taproot will not control it because it will regenerate from the remaining portion of the taproot. Poorly maintained open turf areas allow the establishment of dandelion. Frequent mowing to remove the flowers will reduce the spread of viable seeds. Seedlings can be controlled with isoxaben before they emerge. Postemergent treatment of 2,4-D will control dandelion; products containing MCPA and MCPP are less effective than 2,4-D. Dicamba is not effective for controlling this weed.

ENGLISH DAISY. English daisy is a perennial winter weed that is most common in cool coastal climates. It is difficult to control, but products containing dicamba will reduce infestations. Repeat treatments are required since regrowth can occur and seedlings are common.

GOOSEGRASS (SILVER CRABGRASS, WIREGRASS). Goosegrass seedlings are often confused with crabgrass, but goosegrass germinates later in spring, is darker green, grows in tufts, and has a white or silvery color near the flattened stem bases. This annual weed is normally found on compacted soils or areas of heavy wear. Preemergence applications of oxadiazon have been helpful in the control of goosegrass.

GREEN KYLLINGA. This perennial sedge is a prolific seed producer that also spreads by rhizomes. It has been found in the southern coastal counties and in the Sacramento region. It is often found in areas that are frequently irrigated, have standing water, or where soil remains wet. Repeated applications of MSMA, halosulfuron, or combinations of these two seem to be the best control.

KIKUYUGRASS. Like bermudagrass, kikuyugrass is a perennial weed that is found in south and central coastal counties and in parts of the Sacramento and San Joaquin valleys. Frequently, kikuyugrass is mistaken for St. Augustinegrass. A quick way to tell them apart is to examine their leaves: kikuyugrass has pointed leaves with hairy stems, St. Augustinegrass has short, blunt leaves with no hairs. Most cultural practices will not reduce kikuyugrass invasion. Repeated postemergent applications of MSMA will reduce kikuyugrass in warm-season turf. Repeated triclopyr or triclopyr plus MSMA applications have controlled kikuyugrass invasions into cool-season turf. Repeated applications of quinclorac alone or in combination with MSMA have limited kikuyugrass in warm-season turfgrass.

NUTSEDGE. Yellow and purple nutsedge, sometimes called nutgrass, are serious perennial weeds in turf. Both produce an extensive system of underground tubers from which they can regenerate. Nutsedge is very difficult to control once it is established in turf. When establishing turf, try to plant in seedbeds that are free of nutsedge. Small localized infestations of nutsedge can be controlled with nonselective materials such as glyphosate applied in repeated applications. Yellow nutsedge may be reduced in turf by multiple postemergent applications of products containing halosulfuron or MSMA. Purple nutsedge is more difficult to reduce. Maintain a closed, competitive turf and avoid overly wet soil.

PLANTAIN. Both broadleaf and narrowleaf (buckhorn) plantain are found as weeds in turf. Poorly maintained open turf areas encourage the establishment of plantain. Postemergent treatment with products containing 2,4-D will control this perennial.

SMUTGRASS. Sometimes referred to as wiregrass. A perennial that spreads by seed and quickly becomes established. Control at first indication with spot treatments of glyphosate. Germinating seeds can be controlled with preemergent applications of oryzalin, pendimethalin, prodiamine, or other grass herbicides.

SPOTTED SPURGE AND PROSTRATE SPURGE. Spurge is an annual weed that germinates in open spaces from March through October. It can be a problem in closely mowed turf that has open areas. Preemergence applications of products containing DCPA, isoxaben, pendimethalin, oryzalin, and trifluralin plus benefin, and oryzalin plus benefin have been helpful in the control of spurge. Postemergent applications of products containing bromoxynil or triclopyr have been helpful in limiting the establishment of spurge. In addition, raising the mowing height and increasing fertility may make the turf more competitive against this species.

WHITE CLOVER. White clover is a low-growing perennial that roots at its nodes. It produces flowers that attract bees to turf areas. It develops readily in turf that is low in nitrogen; add nitrogen in spring and fall. Postemergent application of clopyralid, dicamba, mecoprop, quinclorac, or triclopyr will control white clover.

PUBLICATION

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Weeds
C. L. Elmore, Vegetable Crops/Weed Science, UC Davis
C. A. Wilen, UC IPM Program, UC Cooperative Extension, San Diego Co.
D. W. Cudney, Botany and Plant Sciences, UC Riverside
V. A. Gibeault, Botany and Plant Sciences, UC Riverside
M. A. Harivandi, UC Cooperative Extension, Alameda Co.

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