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Publication #PI-171

Florida Crop/Pest Profile: Sugarcane1

Mark Mossler2

Sugarcane Production Facts

  • In 2006, Florida ranked first nationally in value of sugar produced from sugarcane -- approximately $425 million. That amount was half of the total U.S. value of sugar from sugarcane that year. In general, the total amount of sugar produced from sugarcane in Florida is more than 20 percent of total sugar (from sugar beet and sugarcane) produced in the United States annually (1,2).

  • Florida, Louisiana, Texas and Hawaii are the only areas in the United States where sugarcane is grown commercially. Approximately 400,000 acres of sugarcane are harvested annually in Florida, producing approximately 1.5 million tons of sugar annually (1,2).

Figure 1. 

A stand of sugarcane in Immokalee, FL, 2006.


Credit:

Josh Wickham, UF/IFAS


[Click thumbnail to enlarge.]

  • Sugarcane is Florida's most valuable field crop, worth more economically than the combined value of all other field crops grown in Florida, including corn, soybean, tobacco, and peanuts. In terms of Florida's overall agricultural economy, sugarcane ranks third, behind the greenhouse/nursery industry, which is first in Florida, and the citrus industry, which is second in Florida.

  • All Florida sugarcane is crushed at one of four mills in South Florida. Sugarcane milling companies grow about two-thirds of the cane; the remainder is produced by independent farmers. Sugar mills produce raw sugar, which is refined at two refineries in the region or shipped by barge to refineries on the East Coast. Some sugar is marketed in its raw state (2).

Regions of Sugarcane Production in Florida

Sugarcane, a tropical grass, is adapted to all portions of Florida. However, the commercial sugarcane industry is located in South Florida around Lake Okeechobee, especially in the Everglades Agricultural Area. The vast majority of sugarcane production in Florida (70 percent of the acreage and 75 percent of the tonnage) is produced in Palm Beach County. The remainder of commercial sugarcane production in Florida occurs in the adjacent counties of Hendry, Glades, and Martin (2). While most sugarcane is grown on muck organic soils -- which predominate near Lake Okeechobee -- approximately 20 percent of Florida's commercial sugarcane production is on sandy mineral soils (3).

Sugarcane Production Practices

Sugarcane is a multi-year crop and can be grown perennially in Florida. Sugarcane is propagated vegetatively. Following harvest of the first “plant cane” crop, the regrowth (“ratoon cane”) is harvested about once each year until plant populations decline. Typically, an average of three annual crops will be harvested from a sugarcane field before the field is plowed under and replanted.

The majority of sugarcane is planted from September through December. Portions of a mature sugarcane field are reserved to grow “seed cane” -- whole, mature stalks cut directly from the field, either by machine or by laborers using machetes.

Stalks of seed cane are dropped in furrows, cut by hand into smaller pieces, and covered with soil 3 - 8 inches deep. If a sugarcane field is harvested early enough in the growing season (before January), the field will likely be replanted to sugarcane (termed successive planting). If the field is harvested at a later date, replanting may be delayed until the following season. During this fallow period, the field is often planted to another crop, such as rice or sweet corn (termed regular or fallow planting).

In 2005-06, 30 percent of the sugarcane crop in Florida was plant cane, and 70 percent was ratoon cane (2,4). During that same growing season, approximately one-third of the sugarcane was planted successively while the remainder was planted following a fallow period or rotational crop (2,4).

Sugarcane is harvested from late October through mid-April. Sugar yields are typically higher as the weather turns cooler. In order to complete the entire South Florida sugarcane harvest within the optimal time frame, some fields must be harvested before sugarcane plants have reached maximum yield potential. Consequently, research has examined which cultivars should be harvested in early-, mid- or late-season (5). Glyphosate is also used as a ripening agent for early harvest (6).

The fields are burned to remove field trash, and then mechanically harvested cane is loaded onto trucks or rail cars to be transported to the mill.

Worker activities. The only part of sugarcane cultivation that requires field workers is planting, which is 85 percent conducted manually. Approximately 120,000 acres are planted each year, and a single worker may plant up to five acres per day (4).

Insect/Mite Management in Florida Sugarcane Crops

Most sugarcane is resistant to insect pests that are common in semi-tropical environments, but some pests still infest sugarcane. These pests include the following: sugarcane borer, white grubs, wireworms, yellow sugarcane aphid, and lesser cornstalk borer. Weather and cultural practices play a role in the level of pest pressure present from one season to the next (7).

Insect and Mite Pests in Florida Sugarcane Crops

Sugarcane borer

The sugarcane borer, Diatraea saccharalis, is the larvae of a moth. Sugarcane borer is an important above-ground pest of sugarcane in Florida. All varieties of sugarcane currently grown in Florida are susceptible to sugarcane-borer infestation, but different sugarcane varieties exhibit variation in damage and yield losses. Although this moth's principal host is sugarcane, many other grasses have been reported as alternative hosts.

Damage results from the sugarcane borer larvae tunneling into the stalk, causing loss of stalk weight (tonnage/acre) and sucrose yield. Weakened stalks are also subject to breaking and lodging. Additionally, the borer's tunneling into the stalk allows points of entry for secondary invaders. Sugarcane borer infestation early in the sugarcane plant life and boring near the shoot meristem can also kill the shoot, resulting in "dead heart" (7).

Regular scouting is the foundation of an Integrated Pest Management Program (IPM) for sugarcane-borer control. Scouting is necessary to estimate the pest-infestation level and beneficial borer parasites. A regular scouting program will also increase the chances of detecting other pests that may be damaging the crop (7). Sugarcane fields should be scouted every two or three weeks from March through November. One Florida sugarcane company scouts each 40-acre field in at least four locations within the field. At each location, five stalks are randomly sampled from each of five stools spaced 10 feet apart (five stalks/five stools/location).

Borers must be detected before they tunnel extensively into stalks so that, if necessary, control measures can be applied before any damage to stalks occurs. Characteristic signs that plants are infested are pinholes in leaves, tiny holes into midribs, holes into stalks, and frass (light-brown, fibrous waste material) at these holes. An infestation of borers cannot be positively identified until the sugarcane borers are actually observed. Scouts should examine leaves, the whorl, and behind leaf-sheaths, as well as splitting open stalks to detect borers tunneling inside stalks. Detecting two to three live larvae per 100 sampled stalks is generally thought to be enough to cause concern about economic damage (7).

One study of five commercial varieties showed that an average of one bored internode per stalk reduced sugar yield by an average of 5.6 pounds per ton of sugarcane. The range of loss was from 2.3 pounds per ton of sugarcane to 6.7 pounds per ton of sugarcane. Another investigation showed bored internodes produce 45 percent less sugar than undamaged internodes. Interestingly, certain localized regions of the Everglades Agricultural Area seem to be considerably more prone to borer infestations. Environmental explanations are presumed, but definite reasons are not clear (8).

White grubs

Also found in Florida sugarcane fields are white grubs, the larvae of several beetle species of the genera Ligyrus, Cyclocephala, Phyllophaga, and Anomala. Of these grub pests, the species Ligyrus subtropicus is the most abundant, causes by far the most damage to sugarcane, and, as a result, imposes the greatest economic loss for sugarcane growers. These pests tend to infest sugarcane in muck soils, damaging sugarcane by feeding on roots and underground stems. The first symptom of infestation is a yellowing (chlorosis) of the leaves, a condition usually followed by stunted growth, dense browning, lodging, plant uprooting, and, in heavily infested areas, death of the plant. Symptoms may appear as early as September.

Fields of plant cane usually have little or no grub infestation (7,9). Instead, damage from an L. subtropicus infestation is usually more severe in ratoon crops and most evident around the edges of a field, the area where the infestation usually begins. From there, the infestation slowly spreads in an irregular pattern throughout the field. Sugarcane fields infested with L. subtropicus may need to be replanted because ratoon regrowth and productivity can be severely reduced by this pest. Heavily infested areas may not be worth harvesting.

Growers use cultural-control practices for sugarcane grubs. Discing infested fields kills many grubs and allows birds to kill many more. Additionally, planting rotational crops for a weed-managed fallow period and short-term flooding of the standing crop are common methods of grub control in Florida.

Wireworms

Wireworms, the larval stage of click beetles, may cause severe damage to numerous crops in Florida, including sugarcane. At least 12 species of wireworms have been found in South Florida, but only the corn wireworm, Melanotus communis, is considered to cause significant economic damage to sugarcane. Traditionally, M. communis has been a more important pest of sugarcane grown on muck soil than sugarcane grown on sandy soil (7,10).

Generally, wireworms are a pest of newly planted sugarcane and only rarely a pest in ratoon sugarcane. Wireworms feed on the buds and root primordia during germination of sugarcane seed pieces. After germination, wireworms feed on shoots and roots. Most of the injury to young shoots is near the point where the shoots join the seed piece or ratoon stubble.

Wireworm injury can be identified as relatively large, ragged holes cut into buds or young shoots. The death of buds and young shoots leads to stand reductions. Wireworm injury to sugarcane also facilitates the entrance of the fungus that causes sugarcane red rot disease (7,10).

Yellow sugarcane aphid

Yellow sugarcane aphid (YSA), Sipha flava, is a small, yellow aphid with short legs, antennae and mouth parts. The aphid's body is covered in short, stiff hairs. Aphids are born live, not from eggs, and take 2 - 3 weeks to develop to reproductive adult stage, at which point the aphid can produce 3 - 5 nymphs per day for another 2 - 3 weeks. Winged forms of the aphid are produced under crowded conditions when the sugarcane plant is beginning to suffer significant damage.

Natural enemies of YSA include 10 species of ladybird beetles and several species of flower flies. These beetles and flies can greatly reduce YSA populations. Additionally, heavy summer rains usually reduce YSA populations to a low level. However, reduction in the size of a YSA infestation by such means may not occur before the aphids have caused plant damage (7).

Yellow sugarcane aphids cause rust-like reddening and death of sugarcane leaves. Reduced growth and reduced tillering result when these aphids feed on very young plants. Longer, faster-growing leaves and internodes are some of the results of YSA feeding, as well as thinner, lighter stalks with shorter node lengths and narrow widths. Prolonged feeding by large populations of YSA can cause plant death.

After YSA has been brought under control, new sugarcane growth emanating from previously YSA-infested sugarcane will have node lengths and leaf dimensions similar to sugarcane plants that have not been infested with YSA (7). However, node diameters on this new growth will likely be smaller than if the crop had not been infested with YSA. As a result, thinner stalks can be expected from previously YSA-infested plants. These lighter-weight stalks will contain less accumulated sugar; thus, a decline in overall sugar yield can be expected from a crop even after YSA has been brought under control (7).

Aphid populations can build quickly to numbers too numerous to count for sampling purposes. Leaf damage is a good indicator of season-long effects on growth and yield. Leaves with less than 50 percent green tissue can be quickly counted and averaged over an area to compare long-term effects of YSA feeding with the relative size of the infestation. Resistance appears to be a viable control strategy since YSA shows a preference for certain cultivars (7).

Lesser cornstalk borer

The larva of the lesser cornstalk borer moth, Elasmopalpus lignosellus, is a slender, brown worm with creamy-white to bluish-green bands, 1/2-inch to ¾-inch long when full grown. The lesser cornstalk borer larvae bore into young plants at or below the soil surface and usually cause a "dead-heart" similar to damage caused to sugarcane by the sugarcane borer or wireworms. Damage above the growing point appears as rows of holes in emerging leaves, evidence of lesser cornstalk borer feeding on developing leaf whorls at or below the growing point.

Larvae of the lesser cornstalk borer construct a silken tube in the soil; the tube extends outward from the cane plant. The larva pupates in this burrow and transforms into a small moth. The presence of these silk tubes and/or a small, circular entrance hole distinguishes dead-hearts caused by lesser cornstalk borers from those caused by wireworms.

The life cycle of the lesser cornstalk borer ranges from 38 - 65 days. Generations overlap considerably because of the mild South Florida winter, with no sharp seasonal breaks in populations. Most damage resulting from this pest occurs to young sugarcane plants during cool, dry periods. Ratoon cane usually recovers better from lesser cornstalk borer attack than does young plant cane. The protection this pest gets from its silk tube makes parasites of the lesser cornstalk borer inefficient as biological control agents and also makes chemical control measures difficult (11).

Cultural Management of Insects and Mites in Florida Sugarcane Crops

To manage sugarcane borer economically, use sugarcane varieties that exhibit resistance to infestation and damage. Varieties highly susceptible to the sugarcane borer are eliminated during the breeding program that develops new varieties for commercial release. Other important cultural-control tactics include destroying cane trash and stubble in infested fields and using seed pieces free of borer damage (8).

For white grubs, discing infested fields, crop rotation, and short-term flooding in the standing crop are effective methods of control. The best time to kill grubs by flooding is in August, when water temperatures are warm, rainfall is abundant, and feeding damage by the grubs is just starting (9).

For wireworms, flooding can be effective with a minimum of six weeks of continuous flooding during the summer. Longer flooding durations are needed during colder months. Flooding during late spring and summer will kill the wireworms and prevent egg-laying by the adult click beetles. Flooding fallow fields or growing rice as a rotation crop reduces the need to use a soil insecticide at sugarcane planting the following fall (10,12).

For yellow sugarcane aphids, several methods can assist sugarcane resistance to damage. These methods are variety-dependent and include tolerance and antibiotic effects on aphid development. Winged YSAs usually restrict their primary colonization to susceptible cultivars, including the following: 'CP 61-620', 'CP 72-1210', 'CP 72-2086', 'CP 80-1827' and 'CP 89-2143'.

Additionally, red imported fire ants, predatory earwigs and many species of ladybird beetles exert some control over these aphids. Heavy rains are also helpful to dislodge aphids, washing the pests from the sugarcane plants (11).

Biological Management of Insects and Mites in Florida Sugarcane Crops

Alabagrus stigmatera and Cotesia flavipes are important wasp parasitoids of the sugarcane borer larvae in Florida. A. stigmatera is a large, solitary (one-per-host) parasite and active all year. C. flavipes is a small, gregarious (many-per-host) parasite and usually most active after July. C. flavipes is the most important parasitoid. C. flavipes, an endoparasite (parasite that grows within the host), injects eggs directly into the borer larvae.

Whenever sugarcane borer infestation approaches the economic-injury threshold, sugarcane borer larvae from the infested field should be dissected to determine the level of parasitism. If 50 percent or more of the sugarcane borer's larvae are parasitized, insecticides are not recommended. Insecticide applications may harm the parasite population without gaining additional control of the sugarcane borer.

Cotesia flavites is an introduced parasitic wasp that has become established in Florida. Cotesia and the red imported fire ant are effective biological control agents for the sugarcane borer. Augmentative releases of Cotesia parasitoids have been highly effective for managing the sugarcane borer in sugarcane grown in Florida, Brazil, Costa Rica (8) and Jamaica.

Chemical Management of Insects and Mites in Florida Sugarcane Crops

Soil insecticides are used on about half of new plantings of sugarcane in Florida in any given year. Ethoprop and phorate are equally used at about 1 lb ai/A to control wireworms when infestation levels are high. Approximately 2,000 acres of sugarcane in Florida are treated yearly with carbofuran at 0.5 lb ai/A to control lesser cornstalk borer when damage levels are high. However, in 2008 the U.S. Environmental Protection Agency (EPA) announced plans to cancel registration for carbofuran. Other carbo insecticides registered for sugarcane in 2008 in Florida were azadirachtin, B.t., carbaryl, cyfluthrin, cyhalothrin, esfenvalerate, and pyrethrins +/- rotenone, spinosad, and tebufenozide. Methoprene is available for control of fire ants.

Disease Management in Florida Sugarcane Crops

Although there are many sugarcane diseases throughout the world, few such diseases have affected Florida sugarcane historically. For example, until 2008, no fungicides were used on Florida sugarcane to control rusts. Plant breeding programs designed to develop rust-resistant varieties have historically kept brown rust impacts under economic thresholds for any given growing season. However, orange rust was discovered in Florida in 2007. This disease may require growers of susceptible cultivars -- such as 'CP 80-1743' and 'CP 72-2086' -- to use fungicides to maintain acceptable yields.

Disease Pests in Florida Sugarcane Crops

Brown Rust

Sugarcane production in Florida has been affected by brown rust (Puccinia melanocephela) since 1978. This fungal pathogen is now found almost everywhere sugarcane is grown throughout the world. The spread of brown rust has had considerable economic impact. As a result, the practice of screening new cultivars for resistance has become an integral part of Florida sugarcane breeding programs. However, due to genetic variability within the pathogen population, resistance to brown rust has not been stable. For example, 'CP70-1133', an important resistant variety grown for years without symptoms is now classified as moderately susceptible. Other important commercial clones have demonstrated increasing susceptibility to sugarcane rust over time (13).

Assessment of yield loss due to brown rust is difficult, but realistic estimates have been obtained. During 1988, rust was particularly severe on 'CP 78-1247' in Florida. A comparison of yields from 'CP 78-1247' that year with a variety of equal yield potential revealed that yield losses due to brown rust were nearly 40 percent (averaged over 13 different locations in Florida where the varieties were grown side-by-side).

Another study of sugarcane-yield loss -- conducted by establishing a nearly disease-free check using a fungicide as a means for comparison -- demonstrated yield losses of 20-25 percent on a moderately susceptible sugarcane variety, 'CP 72-1210'. This variety dominated the Florida sugarcane industry during the late 1980s, occupying more than 60 percent of Florida's sugarcane area. Economic losses on 'CP 72-1210' in 1987 - 88 were estimated as surpassing $40 million using a conservative estimate of 20 percent yield loss (13).

Brown rust is a leaf disease. The earliest symptoms are small, elongated, yellowish spots, visible on both the top and bottom leaf surfaces. The spots increase in size, turn brown to orange-brown or red-brown in color, and develop a slight, but definite chlorotic halo.

Lesions resulting from brown rust are seldom more than 1-3 mm in width. The lesions typically range from 2-10 mm in length, but occasionally reach 30 mm in length (14). The symptoms of brown-rust infection are usually most numerous toward the leaf tip, becoming less numerous toward the base. Pustules, which produce spores, develop on the lower leaf surface although certain sugarcane cultivars may develop pustules on the upper leaf surface. Pustules may remain active over a considerable period of time during cool seasons of the year with long dew periods.

Environmental factors most influential for rust development are leaf wetness and cool-to-moderate atmospheric temperatures. Several hours of free moisture on the leaf surface at a favorable temperature is necessary for successful spore germination, infection, and spread of the disease. While long dew periods and rainfall events both contribute to leaf wetness, rainfall events may not be as favorable for rust development. Heavy rains tend to remove spores from the atmosphere, and the spores are ineffective if they land on the soil, rather than on leaves. Increased soil moisture also favors rust infection by increasing humidity within the canopy and, thereby, lengthening the duration of leaf wetness.

In Florida, brown rust is most severe from February to May, when atmospheric temperatures are cool-to-moderate. Newly planted sugarcane plants, from 3 - 6 months in age, are more susceptible to brown rust than is ratoon cane (13). It appears, further, that plant cane is more susceptible to brown rust than is ratoon cane.

Eventually, lesions on sugarcane leaves affected with brown rust will darken, and the surrounding leaf tissues will become necrotic. On highly susceptible varieties, large numbers of pustules may occur on a leaf, coalescing to form large, irregular necrotic areas. High rust severity may result in premature death of even young leaves. Severe rust infections can cause reductions in both stalk mass and stalk numbers, thereby reducing cane yield (13).

Orange Rust

Previously, orange rust was known as a minor disease of sugarcane in Asia and Australia. The causal organism of orange rust (Puccinia kuehnii) was found in Florida sugarcane in July 2007 and was also detected in sugarcane fields in Costa Rica, Guatemala and Nicaragua (15).

Orange rust caused an estimated 10 percent loss on susceptible sugarcane varieties in Florida in the late summer of 2007. In the late spring of 2008, more orange rust was observed on susceptible Florida sugarcane varieties, and the disease appeared earlier in the season (16).

Plant cane and ratoon crops appear to be equally susceptible to orange rust. Mature cane is as susceptibe as young sugarcane plants, and the disease persists through hot summer months. The biology of orange rust is similar to that of brown rust. However, varietal resistance to brown rust does not simultaneously confer resistance to orange rust. For example, the variety CP80-1743 has fairly high resistance to brown rust, but not to orange rust.

One third of the overall area planted in sugarcane in Florida is planted with varieties that are susceptible to orange rust, including 'CP80-1743' and 'CP72-2086' (16). Researchers are currently determining whether orange rust is affecting 'CP89-2143' in two locations in Florida. This variety comprises about 20 percent of the acreage planted in sugarcane in Florida (16).

Non-Chemical Management of Disease Pests in Florida Sugarcane Crops

Planting resistant varieties of sugarcane is the best means of controlling rusts on sugarcane. However, resistance has not been stable or durable on certain varieties because of the development of rust variants. It is highly recommended that growers diversify their varietal holdings for this reason. Such diversification is an effective means of limiting risk of yield loss and reducing the likelihood of a new race of rust evolving.

Varietal diversification may also play an important role in holding down overall area-wide disease pressure, thereby reducing the natural-selection pressure for one particular rust variant. A general rule of epidemiology suggests that varietal diversification may assist in preserving the durability of host-plant resistance in currently resistant varieties (13).

Soil factors identified with high levels of rust infection on sugarcane include low soil pH and/or high fertility, so avoid growing susceptible varieties in areas with these soil conditions. Sugarcane grown in fields that have received recent applications of nutrient amendments is typically prone to rust. If possible, plant such fields with varieties that have durable rust resistance(13).

Chemical Management of Disease Pests in Florida Sugarcane Crops

Few effective disease-management tools are available for sugarcane. Propiconazole is available as a dip treatment for plant-cane pieces, and phosphorous-based fungicides are registered for foliar application. However, neither of these treatments is greatly effective for a leaf disease, such as rust, that attacks sugarcane 3 - 6 months after planting.

Because of the limited treatments available to control disease in sugarcane, the Florida Department of Agriculture and Consumer Services (FDACS) has declared a crisis exemption under Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) for the use of two fungicides (pyraclostrobin and metconazole) for control of orange rust. It is envisioned that the EPA will issue a three-year quarantine exemption for this use (16).

As of mid-July 2008, approximately 10,000 acres of sugarcane in Florida had been sprayed with pyraclostrobin. The applications cost approximately $30/acre ($25/acre for the fungicide and $5/acre application cost independent of whether it is applied by ground or air).

Weed Management in Florida Sugarcane Fields

Weed control is most critical early in the season, prior to sugarcane-canopy closure over the row middles. Heavy weed infestations can add unnecessary expense to harvesting sugarcane. Additionally, a weed that is allowed to mature and produce seed will multiply weed-control problems for years to come. The most important weed pests in Florida sugarcane production are fall panicum, napiergrass, yellow and purple nutsedge, and pigweeds (18-20).

Figure 2. 

Mechanical cultivation for weed control in sugarcane crops near Belle Glade, FL, 2004.


Credit: Thomas Wright, UF/IFAS
[Click thumbnail to enlarge.]

Weed Pests in Florida Sugarcane Fields

Nutsedge

Yellow nutsedge (Cyperus esculentus) and purple nutsedge (C. rotundus) are important weed pests of most crops in Florida. Both of these perennial sedges are found in disturbed habitats throughout Florida and the southeastern United States. Yellow nutsedge may produce some seed, but reproduces primarily by rhizomes and tubers. The first plant develops rhizomes, which end in tubers that produce new plants. Tuber production is favored by low nitrogen levels and high temperatures (80 - 91 F). Nutsedges are tolerant of high soil moisture and intolerant of shade.

Purple nutsedge can reproduce from tubers when conditions are harsh, making this weed especially difficult to control. Unlike the rhizomes of yellow nutsedge, purple nutsedge rhizomes growing off the first plant produce new plants and tubers in a series (tuber-chains). Purple nutsedge can reproduce by seed and can survive a wide range of environmental conditions, growing well in nearly all soil types and over a range of soil moisture, soil pH, and elevation. Purple nutsedge is also able to survive extremely high temperatures (20).

Pigweed

Common species of pigweed in Florida include smooth pigweed (Amaranthus hybridus), spiny amaranth (A. spinosus) and livid amaranth (A. lividus). Pigweeds are summer annuals with taproots. These broadleaf plants reproduce by seed and can reach heights of 6 feet, creating a very competitive interaction with young sugarcane (20).

Fall panicum

Fall panicum (Panicum dichotomiflorum) is an annual that primarily emerges in spring and summer. Seed germination can occur almost year-round in Florida sugarcane fields. Fall panicum is sensitive to shading and is typically not found in sugarcane once canopy closure occurs. Fall panicum typically reaches a height of 1.5 - 4 feet and has been reported to reach more than 6 feet in height. The growth habit of this weed can range from erect to sprawling, and the plant can form large, loose tufts (18).

Napiergrass

Napiergrass (Pennisetum purpureum) is an enormous, cane-like grass established throughout South Florida. In the sugarcane production areas of South Florida, napiergrass is commonly seen growing along roadsides, on the banks of canals and ditches, and in disturbed or cultivated areas.

Napiergrass, also known as elephantgrass, is of African origin and has been introduced to all tropical areas of the world because of the plant's ability to quickly produce large amounts of biomass. Napiergrass is widely used as a forage crop in Central America, South America, and Africa.

Napiergrass was introduced to South Florida and Texas as a forage crop in the early twentieth century. However, napiergrass is no longer widely used for this purpose in Florida and has become a considerable weed problem in Florida. The Florida Exotic Pest Plant Council has identified napiergrass as an invasive species in South Florida (19). Napiergrass, which has no natural diseases or insect pests in Florida, has been documented in almost 30 counties throughout the state.

Napiergrass produces many small, viable seeds, which are easily dispersed. Napiergrass also has a thick, aggressive rhizome structure.

Non-chemical Management of Weed Pests in Florida Sugarcane Fields

Crop Rotation

Crop rotation patterns will affect weed management for a sugarcane crop. The need for weed management intensifies in successive planting operations due to cultivation, which contributes to germination of weed seeds. Traditionally, the fallow period between final ratoon harvest and replanting of sugarcane has effectively been used to manage troublesome weed populations by means of mechanical cultivation, crop rotation, and flooding.

Flooding fallow fields aids in weed control through the development of an anaerobic environment, where germination of weed seeds and seedling growth are impaired. In any given year in Florida, rice is grown as a rotational crop on approximately 10,000 acres (12,20). Typically, once the rice-growing season is over, these fields are replanted to sugarcane.

Crop Competition

Crop competition for sunlight is one of the most effective means of weed control. A good stand of sugarcane that emerges rapidly and uniformly and forms a complete canopy (shading the row middles early in the season) is effective in reducing weed competition. Loss of sugarcane plants in ratoon crops -- whether due to rodent, insect, or harvest -- creates open spaces in the sugarcane canopy, under which weeds proliferate. A concentrated effort to maintain maximum cane population throughout all phases of production benefits weed-control efforts (20).

Cultivation

Cultivation can suppress weed growth. A height differential must be established between cane plants and weeds to ensure sugarcane plants get the early advantage in the competition for sunlight. Only when the cane plants are growing taller than competing weeds can mechanical cultivation be effective.

Cultivation when weeds are not present -- due to application of a herbicide or earlier cultivation -- is not recommended. Cultivation when weeds are not present can encourage germination of additional weed seeds and remove the layer of herbicide present when soil-applied herbicides are used. Mechanical cultivators must be able to cut through surface debris and thoroughly mix the soil in ratoon crops (20).

Chemical Management of Weed Pests in Florida Sugarcane Fields

Herbicides are routinely used in sugarcane production in Florida, as in commercial sugarcane production elsewhere in the world. The most commonly used materials include atrazine, 2,4-D, asulam, and ametryn. Herbicides used on less than 10 percent of the sugarcane acreage in Florida are metribuzin, halosulfuron, and pendimethalin (21,22). Other herbicides registered for use in Florida sugarcane as of 2008 are carfentrazone, dicamba, diuron +/- hexazinone, flumioxazin, glyphosate, paraquat, and trifloxysulfuron (20).

Atrazine

Atrazine is a restricted-use pesticide and the main herbicide used by sugarcane growers in Florida. Atrazine is applied to nearly all of the sugarcane grown in Florida as a preemergence treatment and sometimes as an early postemergent treatment. Atrazine controls most annual grass and broadleaf weeds. Atrazine is applied at a rate of 3 - 4 lb ai/A. The price of atrazine is approximately $3.50 per pound of active ingredient. The approximate cost of a maximum labeled application (4.0 lb ai/A) is $14/A (23,24). A special local-needs registration allows up to 10 lb of ai/A per crop.

2,4-D

The herbicide 2,4-D is selective against broadleaf weeds when sprayed on the foliage and is routinely used for the management of spiny amaranth, ragweed, morning glory, and many other weeds. This herbicide is applied by ground or air to approximately three-quarters of Florida's sugarcane acreage at a rate of 1.9 lb ai/A (21,23). Higher rates of application are used for large or difficult-to-control weeds, such as alligatorweed. The price of 2,4-D is approximately $3 per pound of active ingredient, and the approximate cost of a maximum labeled application (2.0 lb ai/A) is $6/A (20,23).

Ametryn

Ametryn is applied as a directional or semi-directional spray to annual grass and broadleaf-weed seedlings. Ametryn is applied to approximately 40 percent of Florida's sugarcane acreage. Ametryn is applied by ground or air at a rate of approximately 0.5 lb ai/A (22). The price of ametryn is approximately $7 per pound of active ingredient, and the approximate cost of a maximum labeled application (1.1 lb ai/A) is $8/A (20,23).

Asulam

Asulam is a herbicide applied to foliage of immature seedling grasses. Application may be broadcast overall, directed, or semi-directed in sugarcane at least 14 inches tall. Asulam is applied only once per year. Asulam controls alexandergrass, broadleaf panicum, and other annual grasses. Asulam activity appears slow. Weed growth ceases at the time of application, and weed death may take 2 - 3 weeks.

Asulam is applied by ground or air to approximately 20 percent of Florida's sugarcane acreage at a rate of approximately 1 lb ai/A (22). The price of asulam is approximately $12 per pound of active ingredient, and the approximate cost of a maximum labeled application (3.3 lb ai/A) is $40/A (20,23).

Metribuzin

Metribuzin is applied by ground to a small number of sugarcane acres in Florida. Metribuzin is not registered for use in sugarcane grown on sand soils.

Metribuzin controls most annual grass and broadleaf weeds and is often mixed with pendimethalin. Metribuzin is applied at the time of planting or ratooning and prior to weed emergence or early post emergence.

Metribuzin is applied at a rate of 0.8 lb ai/A (22). The price of metribuzin is approximately $23 per pound of active ingredient. The approximate cost of a maximum labeled application (1.9 lb ai/A) is $44/A (20,23).

Pendimethalin

Pendimethalin provides preemergent control of annual grasses. Additionally, pendimethalin is often mixed with metribuzin or atrazine for broadleaf weed control.

Pendimethalin is applied by ground or air to a small number of sugarcane acres in Florida. Pendimethalin controls most annual grasses and is often mixed with metribuzin. Pendimethalin is applied at the time of planting or ratooning, prior to weed emergence.

Rainfall or shallow cultivation within seven days of application to incorporate the herbicide into the soil is useful to achieve the best efficacy. Pendimethalin is applied at a rate of 3.3 lb ai/A on muck soils and 2.4 lb ai/A on sand soils (22). The price of pendimethalin is approximately $6 per pound of active ingredient. The approximate cost of a maximum labeled application (4 lb ai/A) is $24/A (20,23).

Halosulfuron

Halosulfuron is applied by ground to a small number of sugarcane acres in Florida. Halosulfuron controls purple and yellow nutsedge, as well as some broadleaf weed species. Halosulfuron may be applied to any stage of sugarcane growth. Halosulfuron is applied at a rate of 0.05 lb ai/A (22). The price of halosulfuron is approximately $245 per pound of active ingredient, and the approximate cost of a maximum labeled application (0.06 lb ai/A) is $15/A (20,23).

Nematode Management in Florida Sugarcane Crops

Plant-parasitic nematodes are microscopic roundworms found in soil. Ectoparastic nematodes feed on sugarcane from the exterior of the root while endoparasitic nematodes enter the plant tissue to feed from within. General symptoms of nematode damage to sugarcane plants include stunting, premature wilting, leaf yellowing and related symptoms characteristic of nutrient deficiencies. Stunting and poor stand development tend to occur in patches throughout the field as a result of the irregular distribution of nematodes within the soil. Ratoon cane is generally most susceptible to damage from nematodes (25).

Most species of plant-parasitic nematodes favor sandy-soil conditions and are rarely a problem on muck soils. However, sugarcane grown in sandy areas has the potential for dramatic yield losses from nematodes (25).

Nematode Pests in Florida Sugarcane Crops

Sting nematode (Belonolaimus longicaudatus), an ectoparasite, is the most damaging nematode to sugarcane in Florida. Stubby-root (Trichodorus and Paratrichodorus spp.), ring (Criconemoides and related genera), and stunt (Tylenchorhynchus and Quinisulcius) nematodes are other ectoparasites that may damage sugarcane and are common in Florida. Endoparasites that may damage sugarcane in Florida are lesion (Pratylenchus zeae), lance (Hoplolaimus spp.), and root-knot (Meloidogyne spp.) nematodes.

Non-chemical Management of Nematodes in Florida Sugarcane Crops

Crop Rotation

Rotation with flooded rice crops can reduce populations of plant-parasitic nematodes. Many of the nematodes that feed on sugarcane can also feed on rice under dry conditions. However, because rice is normally grown in standing water, most nematodes are killed by the flooded conditions (25).

Flooding

Flooding can be an effective management strategy for nematode control in sugarcane. The area should be flooded for a 4-week period, then drained and left dry for 2 weeks, and then flooded again for 4 weeks (25). This practice is difficult on sandy soils, where nematodes are most prevalent.

Soil Amendment

Sediment collected in the sugarcane juice clarification process is called filtercake, cachaza, or mill mud. Soil amendment with this substance has been shown to reduce populations of plant-parasitic nematodes on sugarcane. Filtercake can be added as an amendment to sandy areas to reduce nematode damage. The addition of organic matter, including sugarcane filtercake, to sandy soil can also improve plant tolerance and make nematode damage less severe (25).

Chemical Management of Nematodes in Florida Sugarcane Crops

In sandy soils, where nematodes are most prevalent in sugarcane crops, nematicides are infrequently used. Ethoprop, in addition to managing wireworms, may provide nematicidal benefit. The fumigant 1,3-dichloropropene also provides temporary nematode abatement (25).

Vertebrate Management in Florida Sugarcane Fields

Several species of rat feed on sugarcane plants and can in some cases impose measurable economic loss. A special local-need registration for the rodenticide diphacinone exists for sugarcane growers in Florida (24). Zinc phosphide is also registered to control vertebrates in sugarcane fields in Florida. Rodenticides are applied on the margins of sugarcane fields, but are used on less than one percent of the area planted to sugarcane in Florida.

Key Contact

Mark Mossler is a Doctor of Plant Medicine in the Pesticide Information Office, Agronomy Department, University of Florida, Institute of Food and Agricultural Sciences. Dr. Mossler provides pest management and pesticide information for the public and for governmental agencies. Dr. Mossler can be reached at UF/IFAS PO Box 110710, Gainesville, FL 32611, (352) 392-4721, plantdoc@ufl.edu.

References

1.) U.S. Department of Agriculture National Agricultural Statistics Service. 2008. Crop Values 2007 Summary.

2.) Baucum, L.E., Rice, R.W., and Schueneman, T.J. 2006. EDIS Publication SS-AGR-232, An Overview of Florida Sugarcane (http://edis.ifas.ufl.edu/SC032). UF/IFAS Extension, Gainesville, FL 32611.

3.) Gilbert, R.A., Rice, R.W., and Lentini, R.S. 2008. EDIS Publication SS-AGR-227, Characterization of Selected Mineral Soils Used for Sugarcane Production (http://edis.ifas.ufl.edu/SC027). UF/IFAS Extension, Gainesville, FL 32611.

4.) Glaz, B. and Gilbert, R.A. 2007. EDIS Publication SS-AGR-268, Sugarcane Variety Census: Florida 2005 (http://edis.ifas.ufl.edu/SC083). UF/IFAS Extension, Gainesville, FL 32611.

5.) Gilbert, R.A., J.M. Shine, Jr., J.D. Miller, R.W. Rice, and Curtis R. Rainbolt. 2004. EDIS Publication SSAGR221, Maturity Curves And Harvest Schedule Recommendations For CP Sugarcane Varieties (http://edis.ifas.ufl.edu/SC069). UF/IFAS Extension, Gainesville, FL 32611.

6.) C. R. Rainbolt, R. A. Gilbert, A. C. Bennett, J. A. Dusky and R. S. Lentini. 2005. EDIS Publication SSAGR215, Sugarcane Ripeners in Florida (http://edis.ifas.ufl.edu/SC015). UF/IFAS Extension, Gainesville, FL, 32611.

7.) Cherry, R.H., Schueneman, T.J., and Nuessly, G.S. 2001. EDIS Publication ENY 406, Insect Management in Sugarcane (http://edis.ifas.ufl.edu/IG065). UF/IFAS Extension, Gainesville, FL 32611.

8.) Hall, D.G., Nuessly, G.S., and Gilbert, R.A. 2007. EDIS Publication ENY-666, Sugarcane Borer in Florida (http://edis.ifas.ufl.edu/SC011). UF/IFAS Extension, Gainesville, FL 32611.

9.) Cherry, R.H. and Lentini, R.S. 2008. EDIS Publication ENY-664, White Grubs in Florida Sugarcane (http://edis.ifas.ufl.edu/SC012). UF/IFAS Extension, Gainesville, FL 32611.

10.) Hall, D.G., Cherry, R.H., Lentini, R.S., and Gilbert, R.A. 2008. EDIS Publication ENY-665, Wireworms in Florida Sugarcane (http://edis.ifas.ufl.edu/SC013). UF/IFAS Extension, Gainesville, FL 32611.

11.) Hall, D.G., Cherry, R.H., Lentini, R.S., Nuessly, G.S., and Gilbert, R.A. 2002. EDIS Publication ENY-667, Miscellaneous Insect Pests of Florida Sugarcane (http://edis.ifas.ufl.edu/SC014). UF/IFAS Extension, Gainesville, FL 32611.

12.) Schueneman, T., Rainbolt, C., and Gilbert, R. 2005. EDIS Publication SS-AGR-23, Rice in the Crop Rotation (http://edis.ifas.ufl.edu/AG123). UF/IFAS Extension, Gainesville, FL 32611.

13.) Raid, R.N. and Comstock, J.C.. 2006. EDIS Publication SS-AGR-207, Sugarcane Rust Disease (http://edis.ifas.ufl.edu/SC007). UF/IFAS Extension, Gainesville, FL 32611.

14.) Egan, B.T. 1964. Rusts. P. 61-68. In Hughes, C.G., E.V. Abbott and C.A. Wismer. Sugar-cane diseases of the world. Elsevier Publishing Co. New York, NY.

15.) Isakeit, T. 2008. Orange Rust of Sugarcane: A New Disease Threat. Texas A&M Extension document PLPA-FC003-2008. Texas A&M University System.

16.) U.S. Department of Agriculture Orange Rust Conference Calls, Feb., Mar., May and Aug. 2008.

17.) Gilbert, R.A., Shine, J.M., and Rice, R.W. 2007. EDIS Publication SS-AGR-285, Performance of CP Sugarcane Cultivars Grown in Different Locations in Florida (http://edis.ifas.ufl.edu/SC086). UF/IFAS Extension, Gainesville, FL 32611.

18.) Rainbolt, C. and Sellers, B. 2006. EDIS Publication SS-AGR-132, Fall Panicum: Biology and Control in Florida Sugarcane (http://edis.ifas.ufl.edu/SC079). UF/IFAS Extension, Gainesville, FL 32611.

19.) Rainbolt, C. 2005. EDIS Publication SS-AGR-242, Napiergrass: Biology and Control in Florida Sugarcane (http://edis.ifas.ufl.edu/SC071). UF/IFAS Extension, Gainesville, FL 32611.

20.) Rainbolt, C. and Dusky, J.A. 2006. EDIS Publication SS-AGR-09, Weed Management in Sugarcane – 2007(http://edis.ifas.ufl.edu/WG004). UF/IFAS Extension, Gainesville, FL 32611.

21.) Florida Department of Agriculture and Consumer Services. Summary of Agricultural Pesticide Use in Florida: 1999-2002.

22.) CropLife Foundation - Pesticide use database - 2002 sugarcane data for FL, http://www.croplifefoundation.org/cpri_npud2002.htm.

23.) Anonymous pricing data.

24.) Special Local Need Registrations FL-020001, FL-020002, and FL-880018.

25.) Crow, W.T. 2005. EDIS Publication ENY-053, Plant-Parasitic Nematodes on Sugarcane in Florida (http://edis.ifas.ufl.edu/IN529), UF/IFAS Extension, Gainesville, FL 32611.

Footnotes

1.

This document is PI-171, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date, December 2008. Reviewed March 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Mark Mossler, Ph.D., pest management specialist, Department of Agronomy, Pesticide Information Office, UF/IFAS Extension, Gainesville, FL 32611


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.