Spray_calculation_chart.pdf

J.4

APPENDIX B – Calculations for estimating spray application of carbaryl on individual trees

1. Estimating bole surface area* Formula to get bole surface: (pi*d”)/12 * ht’ = sq. ft. of bole surface e.g ((3.14x8”)/12) x 40’ = 83.7 ft2 of surface area for 8” dbh tree

Note that this equation (& data below) assumes a smooth surface. Trees with furrowed bark (e.g., large ponderosa pines) will have a much greater surface area than calculated by this formula (e.g., 65% or more!).

Approximate bark surface area (ft2) by dbh for 30, 40, and 50 foot spray heights**

DBH 30’ 40’ 50’

8 62 84 104 9 71 94 118

10 78 104 131 11 86 115 144 12 94 126 157 13 102 136 170 14 110 146 183 15 118 157 196 16 126 168 210 17 133 178 222 18 141 188 236 19 149 199 249 20 157 209 262 21 165 220 275 22 173 230 288 23 181 241 301 24 188 251 314 25 196 261 327 26 204 271 339 27 212 283 353 28 220 293 367 29 228 304 380 30 236 314 393

**For conifer species except pinyon pine

*Use of two inch size categories such as obtained by using a Builtmore Stick will speed data collection and summarization (e.g. category 10”dbh covers 9-11” dbh trees).

2. Calculations for mixing 2% AI solution Using the label directions, here are the approximate mixing instructions (at this date):

(From labels for Carbaryl 4L, Sevin 4F, Sevin SL, and Sevin XLR; see pages 8, 25, 10, and 27, respectively.

%AI

(active ingredient per label) label's directions for mixing a 2% AI solution per 1 gallon (128 oz) product add n gallons of water

Sevin SL 43.0 5oz per gallon water 25.6 Carbaryl 4L 43.4 5oz per gallon water 25.6 Sevin 4F 43.0 5oz per gallon water 25.6 Sevin XLR 44.1 5oz per gallon water 25.6 Thus, for 100 gallons water add approx. 4 gallons product

NOTE: 1 gallon of product with 43% active ingrediant (AI) into 25.6 gallons of water results in ~1.65% AI mixture by volume (43% AI in 1 gallon product = X% AI in 25.6 gallons water +1 gallon product; X = 44/26.6 = 1.62% AI). When calculated by weight, the label mixture is 1.8% (see pg 7, SERA 2008). This is not quite the 2% of AI recommended but is the label direction and is refered to as 2% AI in these directions. If label directions were not followed and enough water was used to make a solution of 2% product (which is only 43% AI) (e.g. 1 gallon of product into 49 gallons of water to make 50 gallons total) the level of active ingredient would be only 0.86% AI (X=43/50). Field tests show that 2% gives slightly better efficacy than 1%, although both provided 2 years of protection on lodgepole pine (Shea and McGregor 1987). A 1.7-1.8% level is considered comparable to 2% (see Johnson 1996). The 1.7-1.8% AI from the label recommendation will be called 2% AI throughout this document.

3. Estimate number of gallons of 2% AI carbaryl solution per tree size category and for project:

Formula to determine gallons of solution: ft2 bole surface/50 ft2 per gallon solution (check label for changes) e.g. for a 10”dbh tree sprayed to 40’ ht (=104 ft2 bark surface) 104 / 50 = 2.08 gallons per tree of that size for 10 trees in that size category expect to use around 21 gallons

Note the data below uses the equation assuming a smooth surface. Trees with furrowed bark such as large ponderosa pines will have a much greater surface area and use more solution than estimated below (e.g. 65% or more!).

NOTE: Each gallon of 2% AI solution contains ~0.16 lbs of carbaryl AI. (1 gallon Carbaryl4L contains 4 lbs AI; 4 gal. contain 16 lbs; diluted with 100 gallons of water = 16 lbs/100gallons)

DBH (in) Height (ft)

SQFT

surface

no. gal 2% AI solution (1gal/50ft2)

no. trees in size category estimated gallons 2% AI solution*

8 30 62.8 1.3 0 0.0 10 35 91.6 1.8 3 5.5 12 35 110.0 2.2 15 33.0 14 35 128.3 2.6 12 30.8 16 35 146.6 2.9 6 17.6 18 40 188.5 3.8 3 11.3 20 40 209.5 4.2 5 20.9 22 40 230.4 4.6 2 9.2 24 45 282.8 5.7 1 5.7 26 45 306.3 6.1 0 0.0 28 45 329.9 6.6 0 0.0 30 50 392.8 7.9 0 0.0 32 50 418.9 8.4 0 0.0 34 50 445.1 8.9 0 0.0 36 50 471.3 9.4 0 0.0

TOTAL 134.0

ESTIMATED GALLONS 2% AI CARBARYL SOLUTION PER SIZE CLASS and FOR PROJECT (contact your FHP office for more specifics.)

*Actual gallons of solution used may vary with tree species and bark roughness, equipment used, individual applicator, environmental conditions, etc.