Questions for Aquatic Herbicides in Lakes and Ponds :

Blue represents responses by Michael S. Blankinship, Blankinship & Associates , Davis, CA 8/20/09. Identification of Problem 1. If pesticide applicators are required to identify problem weed areas and app lication areas , what methods (including equipment) do you think they would use to perform this activity? Yes, pesticide applicators are absolutely required to correctly identify weed type. This is critical in making correct decisions on pesticide selection. Then, p esticide applicators are in most cases required to obtain a written recommendation for a California Department of Pesticide Regulation

- licensed Pest Control Advisor (PCA). See the attached form. Prior to determining if a pesticide applicatio n is needed, correct target pest identification is critical. Various methods are used and often more than one method is used in an integrated pest management (IPM) approach. Scouting is the general term and involves correct weed identification, locatio n, density evaluation. This is done, by walking, ATV, boat, windshield survey, and aerial survey using either helicopter or plane. We’ve also worked preliminarily with interpretation of IR aerial photography in certain weed types in commercial crops such as tomatoes. As of now, this has not been adopted to aquatic weed management. Locations and densities are commonly plotted using commercially available GIS software. In cases where submersed aquatic weeds are present, bathymetric surveys are commonly e mployed in lakes, ponds, and reservoirs. Ultimately a variety of control measures are considered. These methods are generally broken down into main categories that include: mechanical (cutting, excavating, dredging, aeration, circulation, etc), biologic al (carp, tilapia, nutrient sequestration agents, competing algal additives, etc), cultural (best management practices including exclusion, placement of native species, nutrient control, UV exclusion, buffer strip placement, damage threshold evaluation, etc) and chemical ( pesticide application, growth regulator use).

a. How much time do you think they would spend to identify these areas (i.e. number of hours per waterbody)? The amount of time required to do proper and adequate scouting is highly variable an d depends on many factors, including but not limited to: water body size and depth, access restrictions, different weed type(s), time of year, frequency of re

- infestation, etc.

b. OR how much do you think this weed identification would typically cost (per cit y, county or state)? This is again dependent on the same variables as listed above. Some counties in CA are larger than entire states on the east coast. Further, some irrigation districts were aquatic weed control is done have > 500 miles of canal and/or creek.2. If pesticide applicators are required to identify weed species and conditions that

necessitate weed control measures , what methods (including equipment) do you think they would use to perform this activity? See answer to #1 above.

a. How much time do you think they would spend to identify the species and conditions (i.e. number of hours per waterbody)? b. OR how much do you think this identification would typically cost (per city, county or state)?
3. If pesticide applicators are required to identify sources of the problem (i.e. nutrients, invasive species, etc.), what methods (including equipment) do you think they would use to perform this activity? Same as #1 above.

a. How much time do you think they would spend to identify these sources (i.e. number o f hours per waterbody)? b. OR how much do you think this identification would typically cost (per city, county or state)? Mechanical Control, Biological Control, and Habitat Modification 4. If pesticide applicators are required to implement mechanical control techniques: As mentioned above, it is unusual that control is necessarily mandated to take a particular approach. Instead, a combination of approaches is used.

a. Please use table provided to answer the following questions: 1. How much time do you think they w ould spend on mechanical control? This is impossible to answer because it is highly site

- specific. Below are some costs that are unit costs consistent with research we have done and experience in the field.

2. How much do you think mechanical control woul d typically cost?Activity Number of Hours (Please specify; per waterbody, etc.) Cost (Please specify; per city, county or state, etc.) Weed removal by hand or machine Highly Variable Man: $20K

- $60K/Ac Goat: $500

- $2000/Ac Machine: $1500

- $3000/Ac.
Note (1): The use of mechanical removal in some cases is not advised due to the risk of plant fragmentation and subsequent downstream reestablishment Sediment tilling Highly Variable Machine: $1500

- $3000/Ac
See note (1) above. Soil and vegetation compress ion through “weed rolling” Highly Variable I am unfamiliar with this approach and have never seen it done. It is not applicable for aquatic weeds. Other (please specify): Lots of alternatives. See description above.5. If pesticide applicators are re quired to utilize habitat modification practices: a. Please use table provided to answer the following questions: 1. How much time do you think they would spend on habitat modification? 2. How much do you think habitat modification would typically cost?
Activity Number of Hours (Please specify; per waterbody, etc.) Cost (Please specify; per city, county or state, etc.) Light attenuation Highly Variable This is typically accomplished with dyes put into water. Costs are variable depending on water use, holding time, depth, etc. Costs may range from $50/surface ac to $500/surface ac. Other (please specify):

Pesticide Use 6. If pesticide applicators are required to conduct maintenance activities to minimize potential leaks, spills, and accidental releases of pe sticides or to maintain equipment to ensure effective application and control, how much time do you think they would spend on these activities? (i.e. number of hours per establishment or per applicator)? They are indeed required to do this work. I would say approximately 5

- 15% of an applicator’s daily effort is related to this type of activity. Quantitation on a per establishment or per acre basis is difficult due to large # of variables involved.

a. OR how much do you think these maintenance activities wo uld typically cost (per establishment, city, county, or state?) Again, highly variable depending on the equipment, terrain, weed type, etc. But for the sake of discussion, here is an example: Lets say the burdened cost of a pesticide applicator or weed technician is $25/hr and he works 7 out of 12 months at a FT rate of 2,000 hrs/yr on weed control. This is perhaps a fairly typical # as in CA we do most of our week control work from March to September. There maybe from 1

- 10 of these individual weed technicians per public works department or irrigation district. Lets assume a smaller irrigation district that covers approximately 10K acres and has 2 applicators. The total cost for both individuals is then estimated at $ 60 K. His maintenance activity is o n the low end (5%) is then $ 3000 and highend is $ 9000. Note to in CA that a licensed pesticide applicator needs to take no less than 20 hours of continuing education every 2 years to maintain his/her license. The PCA needs 40 hours/year.Education

7. If pe sticide applicators are required to post information to users (to address weed identification, the role of nutrient availability in weed occurrence and abundance, accidental weed introduction avoidance, and the pesticide product being used for aquatic weed control), how much time do you think they would spend to post this information (i.e. number of hours per waterbody)? This would add between 3

- 10% to there total time spent. These signs have to be prepared, maintained, replaced, and taken down. So, lowend is 7/12 x 4 000 x0.03= 70 hours or highend is 240 hours.

a. OR how much do you think education by posting would typically cost (per

waterbody, city, county or state)? There are too many variables to estimate this cost on a waterbody, city, etc basis.
Us ing the above example, ~$2K to $6K per year per 10K ac irrigation district

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