In January’s Sugarbeet Notes, I discussed the Food Quality Protection Act (FQPA) and the potential effects of the act on pesticide use in sugarbeets. The FQPA requires a review of many commonly used pesticides and establishes a new risk assessment strategy that includes all types of public exposure, including home use and golf courses, to classes of compounds. Higher (more difficult) risk standards will be imposed, but the process of re-registration otherwise remains characterized by administrative uncertainty at this time. The carbamates and organo-phosphates are among the types of compounds that must be assessed first in what will be a multi-year process. These include the most commonly used insecticides and herbicides on sugarbeets.
In April, as part of the FQPA process, the sugarbeet industry under the leadership of Ben Goodwin of the California Beet Grower’s Association and Tom Babb of Spreckel’s Sugar received a small grant from the Department of Pesticide Regulation (DPR) to create a pest management evaluation. The evaluation was to focus on pest management issues and the use of currently registered pesticides that might be lost under the FQPA process. Based on that report, a proposal was solicited by DPR under a competitive grants program for research and demonstration projects on alternatives to the FQPA listed pesticides. The report and the proposal was created in May by a group of industry and university cooperators including specialists, faculty, and CE advisors. I have just learned that the industry’s proposal was not funded. While disappointing, the process of identifying both the most important sugarbeet pest management priorities and alternatives to traditional practices was very valuable for the sugarbeet industry. In the long run priority identification may be more valuable to the state’s sugarbeet industry than any funding that may have come from the DPR program in the short run.
The important pest management issues for sugarbeets are well known. These include improved weed control, the aphid-borne viruses, armyworms (at both the seedling and later crop stages), nematodes, leafhoppers (particularly as vectors of curly top), and root rots and foliar diseases. Priority setting among these different problems has been informal and responsive to recent perceptions and experiences within the industry. Research funding from the industry has been based on consensus among the members of the industry’s research committee, including growers and industry personnel.
The Sugarbeet Pest Management Evaluation (PME) summarizes what is known currently about the complex of pests affecting sugarbeets. These summaries are well-written and provide good, brief statements of current knowledge about sugarbeet pest management. Priority setting was accomplished by thinking about what the most pressing issues would be in the absence of the pesticides on the FQPA list. Examples of the kinds of uses effected include weed management, insect control during stand establishment and statewide curly top management.
Among the herbicides, pre-emergence materials like cycloate (Roneet®) and pebulate (Tillam®), and the most important post-emergence sugarbeet herbicide Betamix® (phenmedipham-desmedipham) and its combinations are included. As Robert Norris stated in his portion of the proposals submitted, it is difficult to imagine a sugarbeet weed control program without these materials. Indeed because of the potential high cost of relying on tillage and hand weeding, it is difficult to imagine an industry being possible without them under current conditions.
Armyworms are another important group of pests identified as a priority in the sugarbeet PME that are controlled within acceptable limits by currently available insecticides. The necessary level of control on older crops remains a matter of judgement because economic thresholds are not well determined. For seedlings established during warm parts of the year, losses of stand or parts of stand to this insect can be very large. If growers attempt to plant sugarbeets to a stand, the loss of newly emerged seedlings must be kept to a minimum. Currently, there are no established alternatives for control of armyworms at the seedling or later stages other than insecticides and damage thresholds are just now being estimated in the stand establishment program.
Curly top virus is controlled through plant resistance, but young seedlings can be damaged if infected early after emergence. Curly top also affects other crops like tomatoes, peppers and melons. The vector of curly top virus, the beet leafhopper (Circicular tenullis), is managed by applying malathion to natural insect nursery areas in the foothills of the coastal range and the southern Sierra Nevada during the winter months in an attempt to reduce their numbers. This management strategy is regarded as successful but it is not clear how long it will continue. The substitution of a seed treatment like imidicloprid (Gaucho®) that is effective against leafhoppers may be a reasonable alternative, provided insect resistance does not develop but it must be evaluated as part of a larger pest management and stand establishment program.
The control of nematodes was considered the most important pest management issue in sugarbeets three decades ago and it is still a difficult issue. Since that time, other pests have displaced nematodes temporarily as the most important issue, but they remain a serious problem in areas where a large amount of land is infested. Traditional nematicidal materials are being lost to the FQPA process or other regulatory programs, or they are becoming too expensive for sugarbeets. New ideas like the use of catch crops which may help reduce nematode populations and the use of alternative nematicides like ozone or biologically based materials must be evaluated.
The FQPA and alternatives to pesticides.
A consensus about the value of currently available pesticides runs through most of the parts of the Sugarbeet PME. Alternatives are proposed but all contributors emphasize that currently available materials will remain necessary for the foreseeable future. Having a diversity of pest management options increases the effectiveness and reliability of each of the individual tools available. A restriction on one part of the pest management arsenal reduces the effectiveness of the others by making them the only option. This is especially true if the loss of a range of pesticides forces reliance on only a few.
Weed management alternatives include increased reliance on new transgenic, herbicide-tolerant sugarbeet varieties. These are not yet available in California because the ones developed so far are unsuitable for our conditions or because the herbicide for which tolerance exists is not yet registered in California (Liberty® or glufosinate ammonium). Trials are underway around the state at several locations and registration of Liberty® is being pursued. Trials with Roundup® tolerant types also are being conducted. Hilleshog and Avanta (the parent company of the Spreckels-Holly seed division) are planning tests in California in the near future. Betaseed also will have sugarbeets with Roundup® tolerance in addition to Liberty® tolerance. I do not expect herbicide tolerance to eliminate the need for existing materials, but rather to simplify and improve weed control in sugarbeets, especially during the layby period.
Seed treatments are an interesting alternative to pesticides applied to soils or plants because the amounts used are much smaller, they are not likely to be lost to the environment in any toxicologically significant way. The materials used, because they are late-generation chemicals, have to pass more rigorous screening than older materials. Disadvantages can include a high cost, and a narrow range of control. For example, Gaucho® is very effective against aphids and leaf hoppers when plants are young, but does not seem to have any activity against lepidopteran pests like armyworms or against mites. An interesting alternative program to control armyworms involves pheromone confusion. Harry Shorey is working on this approach with cooperators in the San Joaquin Valley. It involves mating disruption and population control. This approach shows promise for controlling armyworm numbers in mature crops, but its usefulness for protecting seedlings is entirely unclear at this time and must be evaluated. Some biologically based materials like the baculoviruses deserve wider evaluation as well.
Gaucho® also is effective against beet leafhoppers. But the ability of Gaucho® as a seed treatment to control the spread of curly top is uncertain. Some tests have been proposed for the San Joaquin Valley this fall. Had the industry’s proposal been funded, these tests would have been funded. They may be conducted on a reduced basis.
Those interested in seeing a copy of the sugarbeet Pest Management Evaluation can contact me or Ben Goodwin at the beet growers for a copy. If you can wait until the middle of August, I will post it on a new sugarbeet web page that is being developed. The development of pest management alternatives likely will become a high priority for the sugarbeet workgroup as the FQPA becomes implemented. I encourage you all to suggest novel ideas to help the industry cope with the potential loss of some of its most important pest management tools.