2008 Annual Report
1a.Objectives (from AD-416)
Develop new and modify existing production-year strategies for integrated and sustainable weed and insect management in sugarcane to:.
1)determine the degree of weed control that current and alternative cultural and mechanical controls afford, weed species that are most susceptible, and conditions that affect efficacy; 2)evaluate and provide efficacy data on new chemistries for selective control of weeds and determine compatibility of new herbicides with currently used herbicidal practices;.
3)identify and evaluate a biological control agent for controlling season-long infestations of the SCB; and.
4)identify new sources of SCB resistance within a population of Saccharum spontaneum. Measure the long-term impact of changing agronomic and harvesting practices on weed and insect pest development during a 4-year sugarcane cropping cycle to:.
1)measure the impact of changing agronomic practices on bermudagrass and johnsongrass development and their competitiveness with sugarcane during a 4-year crop cycle and identify synergistic practices that result in optimum weed control and crop yield; and.
2)measure the effects of soil health, fertilizer, moisture, ground cover, and other sugarcane production practices on insect pests and their natural enemies.
1b.Approach (from AD-416)
Field evaluations will be conducted to evaluate new and/or modify existing production-year strategies to include cultivation frequencies, herbicide application timings and placement, and the utilization of post-harvest crop residue blankets for the management of itchgrass, johnsongrass, and morningglory within a sugarcane crop. Synergistic practices will be identified and subjected to further testing. In addition, the efficacy of high-unit activity herbicides in controlling these weeds will be evaluated as new herbicides become available in an attempt to add additional tools to effectively manage weeds. Separate studies will be conducted to evaluate the long-term (4 to 5-year crop cycle) effects of adopting these practices on crop yield and weed development. In an attempt to lessen the industry’s dependence on insecticides for the control of the sugarcane borer, studies will be conducted to evaluate Cotesia flavipes as a biological control agent for controlling season-long infestations of the sugarcane borer; to identify and develop germplasm with increased resistance to the sugarcane borer, and to assess the effects of sugarcane planting date, soil fertility levels, and post-harvest residue blankets on the population of the sugarcane borer and foraging predators to include the red imported fire ant.
The experimental herbicide, mesotrione, controlled red morning glory and provided residual control comparable to the standard atrazine herbicide treatment. Doveweed was controlled with postemergence applications of the herbicides metribuzin, paraquat, and paraquat plus atrazine, and with preemergence applications of metribuzin, mesotrione, hexazinone + diuron, and flumioxazin. In fallow fields, two or more applications of the herbicide glyphosate were required to control bermudagrass regardless of tillage regime. Bermudagrass control was 90% or more with at-planting applications of herbicide treatments containing clomazone + diuron, metribuzin, or terbacil. National Program Action Plan Component VIII (Chemical Control of Weeds) Subcomponent VIII.D (New Herbicides).
Results indicate that Cotesia flavipes, a parasite of the sugarcane borer (SCB), does not work well in sugarcane with no above-ground internodes. Greenhouse studies suggest that C. flavipes can utilize sugarcane borer in wild grass species such as johnsongrass and vaseygrass during the winter and spring months when sugarcane has no above-ground internodes. Refuge sites were established near a sugarcane field and attempts are ongoing to establish C. flavipes in these weeds. National Program Action Plan Component V (Pest Control Technologies) Subcomponent V.A (Traditional Biological Control).
Progeny of a cross between a SCB resistant breeding cane (US 02-95) and a new series Saccharum spontaneum (MPTH 97-3) were damaged less in the plant-cane crop than either parent. Progeny that demonstrate good yields and resistance to the SCB were returned to the crossing house in 2008 for another cycle of backcrossing. National Program Action Plan Component V (Pest Control Technologies) Subcomponent V.B (Breeding for Host Plant Resistance).
The impact of tillage, harvest residue management, and herbicide placement was evaluated in sugarcane infested with bermudagrass and johnsongrass. Results indicate that no-till encourages weed infestation and reduces crop productivity. Burning or brushing harvest residue increased cane yields but increased johnsongrass infestation. Bermudagrass was unaffected. Herbicidal applications of pendimethalin + metribuzin reduced johnsongrass and bermudagrass infestations, but did not increase plant-cane yields. However, first ratoon yields were increased 10% and 30%, respectively, in bermudagrass and johnsongrass infested cane. National Program Action Plan Component X (Weed Management Systems) Subcomponent X.A (Cultural and Mechanical Control).
Yield data suggested that fall infestations of SCB did not carry over into the next year and did not cause yield loss. Additional sites are being sought for further testing. Pit-fall traps were monitored in a plant-cane field containing plots with harvest residue and without residue. Traps continue to be monitored in the stubble crop. Trapping data indicated that leaving harvest residue can reduce populations of the predatory fire-ant by as much as 30%.
NP 304, Component: 3, 8; Problem Statement: 3c, 8d.
IMPACT OF FALL INFESTATIONS OF THE SUGARCANE BORER (SCB) ON SUBSEQUENT SPRING INFESTATION INTENSITY AND SUGARCANE YIELDS
Sugarcane growers plant their crop earlier every year as their farming operations grow in size. This early planted cane becomes an attractive site for SCB moths to lay eggs in the fall. Growers fear that high numbers of SCB during the fall and winter will translate to higher pest populations the following year. Results indicated that the distribution of the SCB in the field may be correlated with soil nutrients; fall infestations did not carry over into the following year; and although correlated with lower yields, there was no clear indication that these infestations were the cause of the yield loss. We conclude that good farming practices can eliminate any threat that late SCB infestations may pose.
NP 304, Component: 3, Problem Statement: c.
DOVEWEED CONTROL IN FALLOWED SUGARCANE
Doveweed infestations are becoming more common in fallowed sugarcane fields that rely on multiple applications of the herbicide glyphosate to eliminate weeds. Results showed that while treatment with the herbicide paraquat provided an adequate burndown of doveweed, that doveweed was able to reestablish through regrowth of controlled plants or emergence of new plants within three weeks of application. The addition of the herbicide atrazine extended acceptable control of doveweed to 10 weeks after treatment. The herbicide metribuzin also provided acceptable burndown and provided continued residual control for 10 weeks after application. Results of preemergence studies using herbicide treatments consisting of flumioxazin, metribuzin, diuron + hexazinone, or mesotrione controlled doveweed at levels of 80% or more up to 9 weeks after treatment. Results of these studies were included in Louisiana State University AgCenter’s Sugarcane Weed Control Guide and were presented by Caleb Dalley at the Southern Weed Science Society meeting in Jacksonville, FL.
NP 304, Component: 8, Problem Statement: d.
|Number of Non-Peer Reviewed Presentations and Proceedings||7|
White, W.H., Reagan, T.E., Carlton, C., Akbar, W., Beuzelin, J.M. 2007. Elachista saccharella (Busck) (Lepidoptera: Elachistidae), A Leafminer Infesting Sugarcane in Louisiana. Florida Entomologist. 90(4):792-794.
Richard Jr, E.P., Dalley, C.D. 2007. Sugarcane response to bermudagrass interference. Weed Technology. 21:941-946.
White, W.H., Viator, R.P., Dufrene Jr, E.O., Dalley, C.D., Richard Jr, E.P., Tew, T.L. 2008. Re-evaluation of sugarcane borer (Lepidoptera: Crambidae) bioeconomics in Louisiana. Crop Protection. 27(9):1256-1261.