Lawn Care - Weeds in Gardens

Short answer: bermuda grass turns white for three broad reasons, and the pattern tells you which. A uniform straw-white after the first frosts is winter dormancy and needs nothing. Papery-white new growth in stripes or along a boundary is herbicide bleaching: mesotrione or topramezone whitening appears 5 to 7 days after spraying and lasts several weeks, and bermuda is on the do-not-use list for mesotrione. Bleached patches with a defined edge in spring or dewy weather are fungal (spring dead spot, dollar spot), and pale, stunted tufts that will not green up point to bermudagrass mites. Powdery mildew, the cause most people search first, is uncommon on bermuda because it is a full-sun grass, and it is a coating that rubs off rather than a change in the leaf. First, look at what kind of white it is Before buying anything, pull a few white blades and ask: is the white on the leaf (rubs off) or in it (the tissue has lost colour)? Is it the newest growth, the oldest, or everything? Is the pattern uniform, patchy with a sharp edge, or in lines (sprayer passes, a fence, the neighbour's boundary)? Is the plant still growing, or stunted? Those answers sort almost every case. What the white looks likeLikely causeQuick test Whole lawn straw-white after nights near freezing, sometimes green-and-tan stripes firstFrost, then winter dormancyCrowns and stolons still firm and pale green inside; timing matches first frost Newest leaves papery white while older leaves stay green; follows spray lines or one side of the lawnHPPD herbicide bleaching (mesotrione, topramezone); glyphosate drift is slower and yellowerAsk what was sprayed within 200 ft (60 m) in the last 2 weeks Circles or arcs of dead, bleached grass, inches to yards wide, as the lawn greens up in springSpring dead spotDig at the edge: roots, rhizomes and stolons black and rotted Sunken straw spots 1 to 8 in (2.5 to 20 cm); leaf lesions bleached with a tan or red-brown borderDollar spotWhite cottony fuzz on the spots at dawn Greasy, matted dark patches 2 to 12 in (5 to 30 cm) with cottony growth, appearing overnight in humid weatherPythium blightBlades feel slimy; patches follow drainage or mower lines White or grey powder on the leaf surface, shaded areas onlyPowdery mildew (rare on bermuda)Rub a blade: the powder comes off and the leaf under it is green Pale whitish-yellow youngest leaves, veins greener; spring or alkaline soilIron chlorosis (nitrogen if older leaves fade first)Spray a test strip with iron; colour returns in days Straw patch 6 to 10 in (15 to 25 cm) with a dark green ringDog urine or fertilizer/salt burnPattern matches where the dog goes or granules spilled Whitish-tan haze standing above the leaves in summerBermuda seed headsThree to seven finger-like spikes per stalk; gone after mowing Pale, stunted tufts with leaves bunched at the nodes; slow to green upBermudagrass mitePeel back a leaf sheath under a 15 to 20x lens: creamy-white, worm-like mites Whitish stubble the morning after a very low mowScalpingExposed stem bases; greens over in about a week Frost and winter dormancy Bermuda is a warm-season grass. After the first light frosts the blades die back to tan or straw-white, often unevenly. The Tulsa Master Gardeners (Oklahoma State University Extension) describe the early stage as "leopard print" or "zebra turf", green and brown patterns that map where soil heat rose and cold settled, and say there is no cause for concern: only the leaf tops are affected, and they were about to go dormant anyway. A few more frosts and the lawn goes uniformly dormant. According to Texas A&M AgriLife, dormant bermuda is straw-coloured until soil at 4 in (10 cm) reaches 65°F (18°C) and nights stay above 60°F (16°C) for several days; full green-up then takes 2 to 6 weeks. The real risk is a spring freeze after green-up, which Texas A&M says can kill 20 to 80 percent of tillers because the plant must grow leaves twice. Clemson HGIC notes bermuda commonly greens up and is burnt back several times in late winter, so both sources say to hold nitrogen until the lawn is well green. A white lawn in winter needs only patience and a light watering in dry, windy spells so crowns do not desiccate; see how often to water grass in winter. Herbicide bleaching Mesotrione (Tenacity) and topramezone (Pylex) are HPPD inhibitors: they stop the plant making carotenoids, so new growth emerges white before it dies or grows out. Bermuda is not tolerant. Syngenta's Tenacity page lists Kentucky bluegrass, tall fescue, perennial ryegrass and centipedegrass as tolerant and states the product is not recommended for hybrid or common bermudagrass, zoysiagrass, seashore paspalum or kikuyugrass. If a lawn service or a neighbour used it near your grass, white bermuda is the expected result. University of Maryland Extension says the whitening appears 5 to 7 days after application and lasts several weeks, and that it reflects blocked chlorophyll production rather than dead tissue, so a single accidental dose on healthy bermuda usually grows out. The same bleaching is used deliberately to suppress bermuda in cool-season lawns. Virginia Tech describes a tall fescue programme of topramezone at 1 oz per acre plus triclopyr at 32 oz per acre, three applications three weeks apart from mid-August, and warns "there likely will be a bleaching of the bermudagrass foliage." Glyphosate drift looks different: slower, yellower and stunted, with symptoms one to two weeks after exposure. There is no antidote for either. Water and mow normally, feed lightly once green growth returns, and resod anything still white after 4 to 6 weeks of growing weather. Fungal diseases that bleach bermuda Spring dead spot This is behind most "white circles in April" questions in the transition zone. Oklahoma State University Extension describes patches "dead and bleached white in color", circular or arc-shaped and from inches to many yards across, with roots, crowns, rhizomes and stolons black and rotted. Infection happens in autumn and early spring while soil stays above 50°F (10°C); damage shows only when the rest of the lawn greens up. Management is timing: no nitrogen after mid-September, dethatch in summer, and where it repeats, two fungicide applications 30 days apart in autumn before soil drops to 70°F (21°C). Patches refill from surrounding plants through late spring and summer, and cold-tolerant cultivars get less of it. Dollar spot Mississippi State University Extension describes lesions that turn "a bleached or straw color" with tan to reddish-brown margins, in spots 1 to 2 in (2.5 to 5 cm) on close-mown turf and up to 8 in (20 cm) on a lawn. Oklahoma State adds the giveaway: white cottony mycelium on the spots during morning dew. It runs from 50 to 90°F (10 to 32°C), peaks at 60 to 70°F (16 to 21°C), and is essentially a hunger disease; both sources call nitrogen the single most effective control. Oklahoma State's figure for bermuda is 5 lb of nitrogen per 1,000 sq ft a year as five 1 lb applications, May to September. Water before dawn so dew dries sooner, collect clippings while it is active, and use myclobutanil or fluxapyroxad every 14 to 28 days only as a backstop (no myclobutanil above 85°F / 29°C). Spots green over in 2 to 3 weeks of growing weather. Dollar spot on bermudagrass: small, round, sunken patches scattered through otherwise healthy turf. Photo: "Turf (Bermudagrass): Dollar spot, prob. caused by Sclerotinia homoeocarpa" by Plant pests and diseases, CC0. Pythium blight and powdery mildew Pythium is rarer on home bermuda but appears in hot, wet spells. The Texas Plant Disease Handbook describes greasy, matted patches 2 to 12 in (5 to 30 cm) with cotton-like growth in rainy, foggy weather and low spots, and notes hybrid bermudas are more susceptible than common. Fix drainage, stop evening watering, ease off nitrogen and raise the mowing height. Powdery mildew, meanwhile, is the least likely answer: NC State Extension lists its hosts as Kentucky bluegrass, fine fescue and perennial ryegrass, favoured by heavy shade and cool humid weather. Bermuda in that much shade is already thinning for lack of light; prune to let sun in, stop evening watering, keep single nitrogen doses to 1 lb per 1,000 sq ft, or switch that area to a shade-tolerant grass. Fungicide is rarely justified. Iron chlorosis, dog urine and salt Iron-deficient bermuda goes pale yellow-white on the youngest leaves first. UF/IFAS Extension explains why it shows in spring: iron stays soluble only minutes at soil pH 7 or above, cold soil slows uptake, and a spring nitrogen feed pushes growth faster than roots can supply iron. A foliar spray of iron sulfate or a chelate at 1 to 5 lb of iron per acre greens the lawn within days and holds up to 4 weeks; Clemson's homeowner rate is 2 oz of ferrous sulfate in 3 to 5 gallons of water per 1,000 sq ft. If older leaves fade first and the lawn looks pale rather than white, it is nitrogen; our grass turning yellow guide separates the two. Dog urine and spilled fertilizer both leave straw-white rounds with a dark green ring where diluted nitrogen fed the edge. University of Maryland Extension gives 6 to 10 in (15 to 25 cm) as typical and heavy watering as soon as possible as the fix; bermuda runners usually close a spot that size within a month in summer. Recovery times are covered in how long burnt grass takes to grow back. Bermudagrass mites If the pale areas are also stunted, with leaves bunched into tufts along the stem, suspect mites. The bermudagrass mite (Eriophyes cynodoniensis) is, in Clemson's words, "a very small, elongate, creamy white or translucent-colored mite that requires a magnification of 15x to 20x to see", and it feeds only on bermuda. Feeding stops internodes elongating, producing the witches' broom tuft, swollen leaf sheaths and, in heavy infestations, dead stolons. A generation takes 7 to 10 days, and the first sign is usually patches that fail to green up in spring. University of Georgia Extension links severity to drought stress plus traffic, and reports that mites move from infested clippings to healthy grass within 2 hours, so clippings must be bagged. Control is mostly cultural: Clemson recommends mowing at 1 in (2.5 cm), bagging clippings, applying 1 in of water after mowing (weekly on clay, twice weekly on sand), and avoiding heavy nitrogen, which increases damage; dethatch in May to remove infested tissue. Clemson states that home-lawn pesticides are not effective against this mite; UGA lists professional options (abamectin, bifenthrin, lambda-cyhalothrin) from spring, repeated every two weeks in severe cases. Expect a full summer to recover, and resod badly thinned areas. All cultivars are susceptible, though some produce fewer brooms; see our note on stress-tolerant bermuda. Seed heads and scalping Two harmless causes. In summer, especially when dry or underfed, common bermuda throws up seed heads, three to seven finger-like spikes on a thin stalk, which dry whitish-tan and give the lawn a pale haze. Regular mowing at Clemson's 1 to 2 in (2.5 to 5 cm) removes them. And if you drop the mower height sharply you expose the pale stem bases that normally sit below the canopy; the lawn looks white-grey the next morning, then greens within about a week if the crowns were not cut. Never removing more than one-third of the leaf in one mow prevents it. A bermudagrass seed head: thin finger-like spikes that turn the lawn a pale haze in summer. Photo: "Cynodon dactylon flowerhead NC1" by Macleay Grass Man, CC BY 2.0. Common mistakes Spraying fungicide on frost-white or dormant bermuda. Check the calendar and the crowns first. Feeding nitrogen to a white lawn in early spring. On bermuda this invites a late-frost setback; after mid-September it feeds spring dead spot. Using a mesotrione product because it is sold as "safe for lawns". It is safe for cool-season lawns and centipede, not bermuda. Mulching clippings from a suspected mite area; they carry mites to the rest of the lawn within hours. Treating mildew in a shaded patch without fixing the light. Bermuda thins there regardless. How long recovery takes CauseWhat to doGreen again in Frost / dormancyNothing; water lightly in dry spells2 to 6 weeks after soil reaches 65°F (18°C) in spring Mesotrione or topramezoneWater and mow normallySeveral weeks; resod if still white after 4 to 6 weeks of growth Spring dead spotAutumn fungicide, no late nitrogenPatches refill through late spring and summer Dollar spotNitrogen, pre-dawn watering2 to 3 weeks Iron chlorosisFoliar iron sprayA few days; lasts up to 4 weeks Dog urine / saltFlush with waterAbout a month in summer, or plug Bermudagrass miteMow at 1 in, bag clippings, irrigate; professional miticideOne growing season Seed heads / scalpingMow on schedule, never more than one-thirdNext mow / about a week Sources Tulsa Master Gardeners / Oklahoma State University Extension – Bermuda Freeze Damage Texas A&M AgriLife – Spring Transition in Bermudagrass Clemson HGIC – Bermudagrass Yearly Maintenance Program Syngenta – Tenacity Herbicide (tolerant turf species) University of Maryland Extension – Chemical Injury: Lawns Virginia Tech – Selective Bermudagrass Control for Lawns (SPES-350) Oklahoma State University Extension – Spring Dead Spot of Bermudagrass Oklahoma State University Extension – Dollar Spot of Turfgrass Mississippi State University Extension – Dollar Spot of Warm-Season Turfgrasses Texas Plant Disease Handbook – Pythium Blight NC State Extension – Powdery Mildew in Turf UF/IFAS Extension – Iron for Florida Turfgrasses University of Maryland Extension – Dog Urine Damage on Lawns Clemson HGIC – Bermudagrass Mite University of Georgia Extension – Bermudagrass Mites (C1343)