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Lesser Cornstalk Borer Damage to Sugarcane and the Effects of Tillage and Harvest Residue Management
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Permanent Link: http://ufdc.ufl.edu/IR00001043/00001
 Material Information
Title: Lesser Cornstalk Borer Damage to Sugarcane and the Effects of Tillage and Harvest Residue Management
Series Title: Florida Sugarcane Handbook
Physical Description: Fact Sheet
Creator: Sandhu, Hardev Singh
Baucum, Leslie E.
Nuessly, Gregg S.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012
 Subjects
Subjects / Keywords: Sugarcane -- Diseases and pests
Corn stalk borer
Sugarcane -- Harvesting
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 Notes
Abstract: This 6-page fact sheet provides an overview of this pest, its damage to sugarcane, and the plant’s response, and describes the results of a study of harvest residue and controlled tillage experiments.
Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Diana Hagan.
Publication Status: Published
General Note: "ENY-454."
General Note: "Original publication date May 2012. This publication is a part of the Florida Sugarcane Handbook."
 Record Information
Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00001043:00001

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ENY-454 Lesser Cornstalk Borer Damage to Sugarcane and the Eects of Tillage and Harvest Residue Management1Hardev S. Sandhu, Leslie E. Baucum, and Gregg S. Nuessly2 1. This document is ENY-454, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 2012. This publication is a part of the Florida Sugarcane Handbook. For more information, contact the editor of the Sugarcane Handbook, Ronald W. Rice ( rwr@u.edu). Visit the EDIS website at http://edis.ifas.u.edu 2. Hardev S. Sandhu, post-doctoral associate, Entomology and Nematology Department, Everglades Research and Education Center, Belle Glade, FL; Leslie E. Baucum, regional sugarcane/agronomic Extension agent II, Hendry County Cooperative Extension Service, LaBelle, FL; and Gregg S. Nuessly, professor, Entomology and Nematology Department, Everglades Research and Education Center, Belle Glade, FL; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 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 aliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim DeanSugarcane Growth and NomenclatureSugarcane is grown year-round in southern Florida and harvested annually between October and late April. New elds of sugarcane are typically planted each year between September and December. Sugarcane is vegetatively propagated by planting segments of mature stalks 3 inches below the soil surface. Sugarcane stalks are segmented about every 6 inches by nodes, and each node has a potential growth point called a bud or bud-eye. As the new primary shoot grows from these bud-eyes, new buds form below the soil surface at each stalk joint (node). Aer several weeks, these newly formed buds sprout to produce secondary shoots. New buds then develop on the secondary shoots and eventually produce tertiary shoots. ese secondary and tertiary shoots are called tillers, and the primary shoot plus all of these tillers are called the stool. Sugarcane is harvested mechanically by cutting mature stalks (the shoots and tillers) within several inches of the soil surface. Aer the plant sugarcane crop is harvested, it is allowed to grow back from the original stool to produce the next years crop. ese subsequent crops are called ratoon crops. Growers typically grow two to three annual ratoon crops aer the initial plant sugarcane crop. is annual cycle of regrowth provides a habitat with year-round food sources and refuges for insects that can re-infest the sugar cane crop aer each harvest. ese pests can also move to surrounding crops in search of new hosts.Lesser Cornstalk Borer (Elasmopalpus lignosellus (Zeller)) Damage to SugarcaneLesser cornstalk borer larvae (Figure 1) are caterpillars that feed on many grasses and broad-leaved plants, causing yield losses in crops like corn, beans, peanuts, sorghum, and sugarcane. e larvae feed on sugarcane shoots and bore into the sugarcane plant below ground level, leaving behind dead or damaged shoots. Shoots are killed when larvae feed into or below the growing point of the shoot (meristematic tissue), causing death to whorl leaves. e symptom caused by the larvaes damage is called dead heart (Figure 2). Dead hearts can be an indicator that the entire plant has been killed. When entire plants are killed, the reduced stalk population stands (fewer sugarcane stalks per acre) result in lower biomass tonnage and reduced sugar yield per acre at harvest. Alternately, if the feeding occurs above the shoot growing point, the resulting damage may appear as either a

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2temporary dead heart (which is later pushed out of the whorl by live tissue expansion below the damaged region), or as several rows of symmetrical holes in young leaves as they emerge from the whorl (Figure 3). Leaves usually break o across this row of holes within a few weeks of expansion, leading to a loss of photosynthetic surface area, reduced growth potential, and ultimately a lower sugar yield at harvest. Lesser cornstalk borer larvae pupate in the soil and develop into dark-colored adult moths with a wing expanse of 5/8 to 1 inch (Figure 4). ese moths are mostly active at night, but also y short distances (5 feet) when disturbed during the day.Sugarcane Plant Response to Lesser Cornstalk Borer DamageSugarcane is highly susceptible to lesser cornstalk borer at critical growth stages, but can compensate for some earlyseason damage by producing tillers from newly forming buds. However, shoots that die in response to lesser cornstalk borer feeding may not produce new tillers. Sugarcanes ability to compensate for early-season damage varies depending on the variety and age of plants at the Figure 1. Lesser cornstalk borer larva (sixth instar). Credits: Hardev Sandhu Figure 2. Dead heart (brown shoots, red arrow) in sugarcane caused by lesser cornstalk borer. Credits: Greggy Nuessly Figure 3. Holes in sugarcane leaves caused by lesser cornstalk borer. Credits: Hardev Sandhu Figure 4. Lesser cornstalk borer adult (female). Credits: Hardev Sandhu

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3time of infestation (Sandhu et al. 2011a). In greenhouse studies, similar levels of damage to some of Floridas commonly grown commercial sugarcane varieties (CP78-1628, CP88-1762, and CP89-2143) resulted in variety-specic growth and yield responses. Under controlled conditions, a lesser cornstalk borer infestation at the three-leaf stage resulted in 60%% dead hearts in CP78-1628 with no signicant biomass yield loss, whereas an infestation in CP88-1762 resulted in 66%% dead hearts and a biomass yield loss of 11%%. Similarly, CP89-2143 infested at this early growth stage had 74%% dead hearts, resulting in a 25%% loss in biomass yield. Averaged across all three varieties, the loss in biomass yield was 15% at the three-leaf stage, 22% at the ve-leaf stage, and 38% at the seven-leaf stage, as compared to control plants (i.e., plants that had not been infested by lesser cornstalk borer larvae). In addition to biomass yield losses, sucrose yield was reduced by 15% at the three-leaf stage, 20% at the ve-leaf stage, and 39% at the seven-leaf stage. When infested at the threeand ve-leaf stages, CP78-1628 and CP88-1762 compensated for some damage by increasing tiller production above that of the control plants. is trend extended into the mature stalks for these two varieties with a net increase in the number of mature stalks compared to the untreated control. However, when CP89-2143 was infested at the three-leaf stage, tiller production was reduced by 18%% and mature stalk production declined by 28%% compared to the control plants. Overall, yield loss was greater for CP88-1762 than for CP78-1628 and greatest for CP89-2143. ese results indicate that both the variety and age of sugarcane plants can have a signicant eect on recommendations for managing lesser cornstalk borer.Monitoring and Damage ThresholdsBased on these results, sugarcane producers are advised to manage lesser cornstalk borer from the rst sign of dead hearts until the seven-leaf growth stage to prevent signicant yield losses. Since yield losses increased when infestation occurred in older plants, scouting eorts should be expanded between the threeand seven-leaf stages. For varieties that compensate for early lesser cornstalk borer damage by increasing tiller production (e.g., CP78-1628), the producer could eectively wait until the rst signs of infestation before initiating management practices without suering a signicant yield loss. In contrast, producers growing varieties sensitive to early damage (e.g., CP892143) should consider using an early warning system to forecast outbreaks and prepare for their management. For example, an early warning system could include a combination of pheromone traps to sample male moth populations near the target sugarcane elds with an assessment of degree-day models for sugarcane growth and insect population development. ese conclusions are based on experiments conducted in a greenhouse where soil, temperature, solar exposure, and lesser cornstalk borer density were controlled and their natural enemies excluded. It is not fully understood how season-long exposure to lesser cornstalk borer and insect population limiting factors (e.g., soil moisture and high summer soil surface temperatures) may aect damage and plant response throughout the sugarcane growing season.Lesser Cornstalk Borer ControlLesser cornstalk borer larvae are protected in the soil by their silken tunnels. ese silken tunnels make it dicult to apply eective chemical and biological control measures. Many insecticides previously used for control of lesser cornstalk borer in sugarcane are no longer registered for this use (e.g., Furadan). Contact your county Cooperative Extension agent for information on insecticide products available for managing lesser cornstalk borer. e natural enemy complex of lesser cornstalk borer, including the tachinid y (Stomatomyia oridensis Townsend), braconid wasp (Orgilus sp. ), and ichneumon wasp (Pristomerus pacicus melleus Cushman), is negatively aected by pre-harvest burning to remove sugarcane leaves from the harvest stream (Falloon 1974). Although few chemical and natural controls are available that eectively control lesser cornstalk borer in sugarcane, research results indicate that harvest residues and other tillage practices could play important roles in managing lesser cornstalk borer.Harvest Residue and Lesser Cornstalk Borere leafy material and tops of plants discarded in the eld during harvest are referred to as sugarcane harvest residue or trash. To reduce transport and milling costs and maximize harvesting eciencies, most commercial sugarcane elds are burned before harvest to remove as much of this leafy material as possible. Sugarcane harvested without a pre-harvest burn is referred to as a green cane harvest, and the leafy material le in the eld is called a trash blanket. is residue oen covers the entire eld to a depth of up to 12 inches. A thick trash blanket le in the eld aer green cane harvesting reduces lesser cornstalk

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4elds, plots with conventional tillage had less damage from lesser cornstalk borer than intermediate tillage, and plots with intermediate tillage had less damage than plots with no-tillage (Table 1). However, lesser cornstalk borer damage was much higher in the burnt cane eld with conventional tillage than in the green cane eld with intermediate tillage. Maintaining the harvest residue near the plants may reduce suitable egg deposition sites near the plants (Bennett 1962), which reduces sugarcane plant damage. In green cane harvested elds, sugarcane biomass yield (tons of cane per acre) and sugar yield (tons of sugar per acre) were greater in plots with intermediate tillage (2008 and 2009 biomass yield = 31.9 and 36.5 tons cane/acre; sugar yield = 4.0 and 5.0 tons sugar/acre) than no-tillage or conventional tillage (Table 2). However, in the burnt cane harvested elds, conventional tillage had greater yields (2008 and 2009 biomass yield = 29.1 and 34.7 tons cane/ acre; sugar yield = 4.0 and 4.8 tons sugar/acre) than other tillage treatments. Dierences in biomass yield and sugar yield among tillage levels are likely the result of dierences in abiotic factors (soil temperature and soil moisture) and lesser cornstalk borer damage to sugarcane. Although the no-tillage and intermediate tillage plots in the green cane harvested elds had similarly low levels of lesser cornstalk borer damage (Table 1), sugar yields in no-tillage environments were typically lower than those in intermediate tillage environments (Table 2). is reduction in sugar yield in the no-tillage treatments has previously been attributed to elevated soil moisture and lower soil temperature in elds covered with trash blankets (Oliviera et al. 2001). However, the intermediate tillage treatments resulted in greatly reduced damage from lesser cornstalk borer (Table 1), while maintaining the same yield as the conventional tillage treatments. In some cases, sugarcane plants may be able to compensate for lesser cornstalk borer damage. However, severe outbreaks of this pest can result in signicant stand losses and yield reductions. Lesser cornstalk borer damage is reduced when trash blankets are le in the elds aer green harvesting of sugarcane. Intermediate tillage of the trash blanket into the soil provides adequate levels of lesser cornstalk borer control while allowing for greater rain percolation and fertilizer penetration. In conventional burnt sugarcane harvested plots, conventional tillage practices resulted in the lowest lesser cornstalk borer damage and also increased biomass and sugar yields. borer damage in the following ratoon crop (Sandhu et al. 2011b). A study was conducted to determine the potential use of this type of trash layer as a mulch to manage lesser cornstalk borer in plant cane. In the study, the trash blanket was manually removed from a neighboring sugarcane eld (following a green cane harvest), and this trash blanket was manually spread across the freshly prepared soil (no trash) of a recently planted sugarcane eld. e imported trash blanket mulch resulted in 5 times fewer dead hearts and 3 times fewer plants with holes in leaves than plots without a trash blanket. Without a trash blanket, ratoon cane suered signicantly greater damage from lesser cornstalk borer compared to ratoon cane where trash blankets were maintained. However, the damage in ratoon cane was much lower overall than in plant cane. e eect of the trash blanket on lesser cornstalk borer damage is not well understood, but trash blankets maintain higher soil moisture levels than in exposed soil. Higher soil moisture levels inhibit egg deposition by adult lesser cornstalk borer moths and increase larval mortality (Leuck 1966; Knutson 1976). ere also may be greater numbers of natural enemies in elds with trash blankets than in elds with bare ground, which could promote reduced lesser cornstalk borer damage.Tillage and Lesser Cornstalk BorerLeaving a thick trash blanket over the eld has been shown to reduce lesser cornstalk borer damage, but this practice can lead to other production challenges. Incorporating the harvest residue (trash) into the soil through tillage can reduce problems with water percolation, fertilizer application, and reduced yields in mechanically harvested green cane elds. In controlled tillage experiments, lesser cornstalk borer damage and sugarcane yield were measured in plots with no-tillage, intermediate tillage, and conven tional tillage treatments in both green cane and burnt cane harvested elds. Sugarcane rows in the conventional tillage plots were cultivated very close (2.5 inches from row center) to the stools, which greatly reduced or eliminated the trash blanket between the rows of sugarcane. In the intermediate tillage treatment, only the center of the interrow spaces ( 6 inches from stools) was cultivated, leaving the trash adjacent to the plant bases undisturbed. e eect of these tillage treatments on lesser cornstalk borer damage was signicant in both green cane and burnt cane harvested plots. In the green cane harvested elds, those with conventional tillage had signicantly more damage from lesser cornstalk borer than those with intermediate tillage or no-tillage treatments. In burnt cane harvested

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5Sandhu, H.S., G.S. Nuessly, R.H. Cherry, R.A. Gilbert, and S.E. Webb. 2011a. Eects of Elasmopalpus lignosellus (Lepidopter: Pyralidae) Damage on Sugarcane Yield. J. Econ. Entomol 104: 474-83. Sandhu, H.S., G.S. Nuessly, R.H. Cherry, R.A. Gilbert, and S.E. Webb. 2011b. Eects of Harvest Residue and Tillage on Lesser Cornstalk Borer (Lepidoptera: Pyralidae) Dam age to Sugarcane. J. Econ. Entomol. 104: 155-63.Summarye ability of lesser cornstalk borer larvae to cause dam age to sugarcane depended on the variety and time of infestation. Equal numbers of lesser cornstalk borer larvae caused more damage in CP89-2143 than in CP78-1628 and CP88-1762. Early infestation of young plants produced more damage, but because of greater compensatory growth response (i.e., plant recovery) during the early growth period, the yield losses were lower than those recorded for late-infested plants. Older plants infested with lesser cornstalk borer did not respond with compensatory growth (did not recover well from lesser cornstalk borer damage), and thus yield losses were more pronounced when older plants suered lesser cornstalk borer damage. CP78-1628 demonstrated the greatest ability to compensate for lesser cornstalk borer damage among the three tested varieties. Lesser cornstalk borer damage can be reduced by trash blankets resulting from green harvesting of sugarcane or through application of harvest residue to cover the soil surface around sugarcane plants. Intermediate tillage may allow greater rain percolation and fertilizer penetration while maintaining low levels of lesser cornstalk borer damage. In burnt cane harvested plots, conventional tillage had the lowest lesser cornstalk borer damage and resulted in increased biomass yield and sugar yield.ReferencesBennett, F.D. 1962. Outbreaks of Elasmopalpus lignosellus (Zeller) (Lepidoptera: Phycitidae) in Sugarcane in Barbados, Jamaica, and St. Kitts. Trop. Agric 39:153-6. Falloon, T. 1974. Parasitoids and Predators of the Lesser Cornstalk Borer, Elasmopalpus lignosellus (Zeller), on a Jamaican Sugar Estate. Masters thesis, University of Florida. Knutson, A.E. 1976. Damage to Corn and the Eect of Soil Moisture on Oviposition and Larval Survival of the Lesser Cornstalk Borer, Elasmopalpus lignosellus (Zeller). Masters thesis, University of Florida. Leuck, D.B. 1966. Biology of the Lesser Cornstalk Borer in South Georgia. J. Econ. Entomol. 59:797-801. Oliviera, J.C.M., L.C. Timm, T.T. Tominaga, F.A.M. Cssaro, K. Reichardt, O.O.S. Bacchi, D. Dourado-Neto, and G.M. de S. Cmara. 2001. Soil Temperature in a Sugar-cane Crop as a Function of the Management System. Plant and Soil 230:61-6.

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6 Table 1. Average lesser cornstalk borer damage (% dead hearts) at dierent sampling time in elds with two harvest methods and three tillage treatments. % Dead hearts Year Sampling time (day of year) Harvest method Conventional tillage Intermediate tillage No-tillage 2008 80 Burnt cane 23.0 26.8 29.1 Green cane 20.2 1.0 0.4 94 Burnt cane 20.8 21.0 27.1 Green cane 12.3 0.2 0 108 Burnt cane 14.6 17.6 18.7 Green cane 7.5 0 0 122 Burnt cane 13.2 16.3 18.9 Green cane 8.8 0.8 0.5 2009 81 Burnt cane 16.8 21.5 23.4 Green cane 11.6 0.7 1.3 95 Burnt cane 15.3 20.1 24.6 Green cane 11.2 0.9 0.9 109 Burnt cane 15.4 20.7 22.2 Green cane 9.7 0.6 1.1 123 Burnt cane 9.2 11.3 13.6 Green cane 6.2 0.7 1.3Table 2. Sugarcane yield measurements comparing eects of harvest method and tillage level in 2008 and 2009. Year Harvest method Tillage Biomass yield (tons of cane per acre) Sugar yield (tons of sugar per acre) 2008 Green No-tillage 30.2 3.9 Conventional 28.5 3.7 Intermediate 31.9 4.0 Burnt No-tillage 26.2 3.4 Conventional 29.1 4.0 Intermediate 27.1 3.7 2009 Green No-tillage 32.9 4.6 Conventional 34.1 4.7 Intermediate 36.5 5.0 Burnt No-tillage 30.7 4.4 Conventional 34.7 4.8 Intermediate 33.1 4.5