JUNE 1946 C: ular No. 93 CHAMBER for FUMIGATING PLANTS with METHYL BROMIDE Construction and Operation I STATION EXPERIMENT AGRICULTURAL INSTITUTE 4 /Ae ALABAMA POLYTECHNIC M. J. Funchess, Director Auburn, Alabama C 0 N T E N T S Page MATERIALS AND EQUIPMENT --------------------------- 4 6 CONSTRUCTION OF CHAMBER---- OPERATION OF CHAMBER --------- ------------------- 19 PLANTS NOT INJURED BY METHYL BROMIDE --------------- ----23 FUM IGATION ------------- ---------- PLANTS PARTIALLY BUT OR COMPLETELY KILLED --BY DEFO- LIATED NOT METHYL BROMIDE FUMIGATION -. --------- -------------------- 24 PLANTS TOO SERIOUSLY INJURED BY METHYL ------------------- BROMIDE TO BE FUMIGATED ---- 24 FIRST PRINTING, 3 M CHAMBER for FUMIGATING PLANTS with METHYL BROMIDE Construction and Operation L. L. ENGLISH, Entomologist AgriculturalExperiment Station G. F. TURNIPSEED, Entomologist State Dept. of Agriculture and Industries METHYL BROMIDE has been used widely in the last few years for fumigating fresh fruits and vegetables, stored grains, and a variety of plants and shrubs for killing insect pests. Research work with methyl bromide as a fumigant was begun in 1938 by the Alabama Agricultural Experiment Station. Particular emphasis was placed on its use for fumigating camellias and azaleas. As the work has progressed, the scope of the study has been broadened. Fumigation schedules have been established for a wide range of temperature, and many details have been worked out. As a result, fumigation of plants is now a practical measure for nurserymen. Reported here are the details for construction and use of a chamber suitable for fumigating plants with methyl bromide. The cost of materials and equipment totals about $200. Methyl bromide is noninflammable. It is a colorless and odorless gas at ordinary temperatures and pressures. In its manufacture, methyl bromide is compressed to the liquid state, and is put up in cylinders and in 1-pound cans. The can contains 262 cubic centimeters and costs about 85 cents. Since liquid methyl bromide boils at about 40 ° F., ordinarily there is enough vapor pressure to force it into the chamber where it quickly turns to a gas. The chamber used for fumigating plants with methyl bromide must be gas-tight and insulated. This is because of the character of the gas and the need to control temperature for a definite period of exposure. [1] The chamber described here was designed without a ventilating duct, in order to simplify construction and to cut costs. Consequently, it is absolutely necessary that the chamber be placed in an open shed where people will not be exposed to the gas when the door is removed for ventilating. Since the fumigation period is relatively short and several loads of plants can be fumigated in a day, a chamber having a capacity of 200 cubic feet was found practical for the average nurseryman. This size chamber has a usable floor area of about 27 square feet. However, the floor area can be increased to about 108 square feet by using three removable decks for fumigating small plants. MATERIALS ard EQUIPMENT FOR CHAMBER A good carpenter should be employed to build the gas-tight chamber: Good workmanship and ability to follow directions are essential. Dressed, dry lumber should be used. Fir is specified for the frame work of the chamber, because it is important to use straight materials. While a little more costly than pine, the additional expense for fir is justified. Less labor will be required in squaring the frames, and less calking will have to be done to make the chamber gas-tight. Material List. The following materials will be needed for construction of the chamber: 2 pcs. 6" x 6" x 8' creosoted pine sills (not shown) 3 pcs. 2" x 6" x 10' fir 2 pcs. 2" x 6" x 8' fir 1 pc. 2" x 6" x 5' fir 1 pc.2" x 6" x 12' fir 5 pcs. 2" x 3" x 8' fir 18 pcs. 2" x 3" x 12' fir 2 pcs. 1" x 3" x 7' fir 4 pes. 2" x 3" x 10' fir 2 pcs. 1" x "x 12' fir Spe. 5/4" x 3" x 6' fir 70 pes. 1" x 6" x 8' #1 pine T & G 14pcs. 1" x 6" x 12' #1pine T & G #1 pine #1 pine 19 pcs. 1"x 2"x 10' #1 pine 3 pcs. 2"x 4" x 12' #1 pine 4 pcs. 1" x 3" x 12' 3 pcs. 1"x 2"x 12' 6 pcs. % "x 4" x 10' ceiling, #1 pine 14 pcs. 1" x 6" x 10' #2 cypress or pine 1 pc. 2" x 2" x 10' oak 8pcs. 1 /2" x 2 " x 7' #1 pine x 4pcs. 1/% 2 /2" 6' #1 pine "x 1 4pcs. /2" x 2 /2" x 8' #1 pine 4 pcs. /4 -round 5' long 4 pcs. /4 -round 6' long 4 pcs. 1/4 -round 8' long [4] 3 sheets 28-guage galv. iron 30" x 120" 10 sheets 28-guage galv. iron 30" x 96" 8 to 10 bags rock wool 1 roll 15-pound builders felt 4 lb. 4d common nails 4 lb. 12d common nails 4 lb. 16d common nails 1 lb. 6d box nails 10 lb. 8d cement coated box nails 6 machine bolts, 1/2" x 9", with 5" threads 6 extra nuts for %" bolts 12 washers for '/2" bolts 1 aircock M & F, %/4" 1 galv. pipe nipple, 1/4" x 4" 1 galv. pipe bushing, % " x /2 " 1 galv. pipe bushing, /2 "x 3/4" 18 lag screws, %" x 83 /2" 18 washers for %" lag screws 4 lag screws, /2" x 6" 1 doz. 3/4%" RH brass wood screws 1 doz. 11/4" FH brass wood screws 1/ doz. 1% " FH wood screws 2 door pulls with screws 7 ft. 1/4" OD copper tubing 1 union for OD copper tubing 1 pc. /2" hardware cloth 10" x 24" 1/4" 1 pc. 6" stove pipe 2 stove pipe elbows 6" 6 door-stop plates (Figure 6.) 2 gal. Ruberoid or Flintkote plastic cement 1 gal. paint, pearl gray, for outside 20 ft. rubber gasket, "x 1" cross section (gasket coated with adhesive on one side, may be obtained at auto supply stores) 20 ft. 12-2 Romex cable 10 ft. 12-guage asbestos covered copper wire 10 lb. #6 HD bare copper wire, or enough to run from inside chamber to nearest water pipe 1 2-circuit porcelain fuse box 4 3" galv. outlet boxes with Romex clamps 1 cover with SP toggle switch, 15 amp. 1 cover with SP toggle switch, 30 amp. 2 plain covers for outlet boxes 6 pony cleat receptacles 6 200-W 120-V lamps 2 15-amp. plug fuses 2 30-amp. plug fuses 2 soldering lugs 5/16" 12 "nail-it" knobs 1 ground clamp for water pipe I roll friction tape 1 roll rubber splicing compound Special Equipment. The following special equipment will be needed for construction of the chamber: 1 Blower unit with bottom horizontal discharge; motor direct connected, 1/8 h.p., 1725 r.p.m., 60 cycle AC current; rotation, counter-clockwise; blower capacity of not less than 350 cubic feet of free air per minute. 1 Methyl bromide applicator, 280-cubic centimeter capacity, with can puncture rack and extension tube for use of 1-pound cans. 2 Thermometers, 0 ° to 120 ° F. range, in 1-degree divisions. (Because of U. S. postal restrictions on use of manufacturers' names in publications mailed free under the Experiment Station's franking privilege, the sources of methyl bromide, the specific blower, and applicator are omitted. This information may be obtained by writing Agricultural Experiment Station, Auburn, Ala.) [5] CONSTRUCTION of CHAMBER The method for building the chamber is given in a step-by-step description, beginning with the floor and sides. Important construction details are given in the accompanying illustrations. Floor Construction (Figure 1). Cut the following pieces fur the floor: 2 pcs. 6" x 6" x 8' creosoted sills (not shown) 7 pcs. 2" x 6" x 4'-10" fir joists 12 pcs. 1" x 6" x 7'-7" T & G floor sheeting 3 pcs. sheet iron 30" x 60" (from 120" sheets) 2 pcs. 2" x 6" x 7'-7" fir side plates pine, 12 pcs. 1" x 2" x 4'-10" subfloor support 72 pcs. 1" x 6" T & C for subfioor to fit between joists #1 I I SUB FLOOR ROCK WOOL: H 11I I I :FELT OVER FLOOR SHEET IRON VER FELT T..G. FLOOR OVER ROCK WOOL III II JOIST SUBFLOOR ROCK WOOL T. FLOORING G. SHEET IRON OVER FELT . I I Ii-. CROSS SECTION OF FLOOR FIGURE 1. Detail of floor construction. [6] Nail joists and side plates together; put in subfloor and add rock wool; then put on 2" x 6" T & G flooring and felt over flooring. Cover with sheet iron. Pieces should come together (not lapped) at the center of the third and fifth joists. Nail sheet iron about every 12 inches with 4d nails. Two Side Frames (Figure 2). The following dimension pieces will be needed for the two side frames: 4 pcs. 2" x 3" x 7'-7" fir plates 4 pcs. 1" x 3" x 6' fir braces to fit 18 pcs. 2" x 8" x 5'-9" fir studs 6 pcs. sheet iron 30" x 72" (cut from 96" sheets) Use double studs on ends and space others as shown. Mortise corner braces into studs. If 2 x 8's have been rough sawed on one edge, use smooth edge for inside and nail flush with plates. Cover inside frames with sheet iron lengthwise of studs. Sheets of galvanized iron should meet at the center of the third and fifth studs. Nail about every 12 inches with 4d nails. FIGURE 2. Framing details of side walls. [7] Rear Frame (Figure 3). Cut the following pieces for build- ing the rear frame: 2 pcs. 2" x 3" x 4'-7/2" to 8" fir plates (check length before cutting, since the end frame must fit snugly between the two side frames when they are erected flush with the edge of the floor) 5 pcs. 2" x 3" x 5'-9" fir studs 2 pcs. 1" x 2" x 12" 2 pcs. 1"x 6" x 11/2" 2 pcs. sheet iron 28" x 72" (check measurements for frame before cutting) FIGURE 3. Framing details of rear wall. [8] Nail plates and studs together as shown, using smooth edges of lumber for inside. Square the frame and nail a temporary brace on the outside. Construct support for thermometer out of two 1" x 6" boards, nailed to 1" x 2" x 12" strips. This support should fit snugly between studs in lower back corner, and flush with inside edge of studs. If for any reason the back of the chamber is not accessible, the thermometer support should be constructed in one of the side frames at the back of the chamber. Cover inside of rear frame with sheet iron, lengthwise of studs. It is highly importdnt that the sheet iron is flush and true with all four outside edges of this frame. Front Frame (Figure 4). For the front frame, cut the following pieces: 2 pcs. 2" x 3" x 4'-7/2" to 8" fir plates (check length before cutting, since the frame must fit snugly between the two side frames when they are erected flush with the edge of the floor) 6 pcs. 2" x3" x 5'-9"studs 2 pcs. sheet iron 13" x 72" (check measurements before cutting) Use double studs for door frames, single studs on ends. Nail together, square up, and nail a temporary'brace on the outside. Cover inside, except door opening, with sheet iron. It is highly important that the sheet iron is flush and true with outside edges of frame. Erection of Frame Work. Before erecting the framework, run a double, continuous line of plastic cement around the floor about an inch from the outside edge with a putty gun. Also run a double line of cement on the sides of studs of end frames where they come together with the side frames. Erect the framework and nail securely together and to the floor. Side frames should be toe-nailed into floor joists. Top Frame. The following pieces will be needed for the top frame: 7 pcs. 2" x 3"x 5'-1" fir joists 3 pcs. sheet iron 80" x 60" 12 pcs. 1" x 3" fir cleats to fit between joists Space joists properly, and square and use temporary braces. Turn frame over and cover with sheet iron, running lengthwise of [9] o I 0) 4 - FIGURE 4. Framing details of front wall. joists. Sheet iron should come together in center of third and fifth joists. Nail about every 12 inches with 4d nails. Run a double line of plastic cement on top of plates of side and end frames with a putty gun. Lay top frame, with sheet iron down, on top of plates. Nail in place. Fit 1" x 3" cleats between joists on top of sheet iron and nail in place with 8d coated box nails. [ 10] :" ::::.....:".....: :. :: ..:.....:. . i FELT I II frz v~t~ S~~s zfs i r :iti: : :;: WO C i}Rfr .:#. iii O L :::'} chambr, pt strip n a \s 1i of felt crosswise of\stu n/badu -. of.stusad ordu with~:s"T& 1"~x erl oth o o h fl ~ trp ro h rock wool between she irn ad otsie wll.(Iftheroc ~t wool is obtaine in roll or ba ::~:::frm,:~;::~ e laed etee it hold studs before boarding up the side.).... Th rckwol holdb placed-~~..~;S. butshould ot be pcked sotightl evenly and firly, tha itEcase bulin ofte he io.Cotne ihante strip of lapped, anther sectionof boards, rck wool, an fel, sountil thewalls: completed on aref Outside 5) sould Beginnin batthebottomof[ placedvenlyadfirml,_but_ woo pcedsotghl PuLtroc Sheeting (Figureciigjoss no,cvrwthfladte bewe T&C lumber. Tri the cornes with 12" x 2 " strips. :~:: Door Stop (Figure 6). Consti~,:~:::~~:~ruc: .ft dorstpacorin o igr 6, usingpieces of2" x 6" an two pieces of 2" x 3" fir.i tw :[:~S::: 11 11 wool is obtained in roll or bat form, it should be placed between taicaebuigfteheio.otuwian tiI ~ chambe, puton a srip o felt II crssiei 5. 1 her FuigUREw5.piee of 2chamberashow apiecationof 2sheetingr S 5X7"P/oe Front W/ Dor Stop Door X Pine 3X5" P/late --E-SECTION 22 A A Head Of Bolts To Spot We lded y Moke 4 from Make 2 from hole oPoe Plate 8- gouge iron DOOR STOP FIGURE 6. IRON PLATES FOR 8- gouge iron DOOR STOP Construction details of door stop. The door stop should provide a 1i-inch flange for the gasket all the way around the door opening. Use great care in locating the holes for the bolts, which are spot-welded to the plates. Apply a liberal amount of plastic cement to that part of the inside wall that is to be covered by the door stop. Also apply plastic cement to the iron plates and force some into the holes through the walls and 2 x 6's. Draw door stop tightly against inside with nut and washer on outside. Do not put on the gasket until the chamber is completed. Deck Supports (Figure 7). Install deck supports according to Figure 7. Locate holes in three studs for 3/8" x 3 " lag screws for each 2" x 3" support. Squirt plastic cement into holes. Also apply cement around holes and over sheet iron joists the full width of the supports. Draw supports tightly against wall with the lag screws. Cut 1" x 6" boards for deck, slightly shorter than inside width of chamber. [ 12 REMOVABLE DEC K I X 2" WOOD STRIPS OVER ' SHEET IRON JOINTS AIR DIRECTION m C W 2X3" DECK SUPPORT LAG SCREWS 0 LL 0 0 _ a FALSE FLOOR METHYL BROMIDE DISCHARGE BLOWER FIGURE 7. Cross section of chamber showing deck supports and subfloor. INSIDE CORNER DETAIL DETAIL OF SHEETI JOINTS OVER STUDS & FIGURE 8. Details for making inside of chamber gas-tight. r[13]1 Making Inside Gas-Tight (Figure 8). Make a liberal and continuous application of plastic cement to sheet iron joints on floor, ceiling, and walls. Fit 1" x 2" wood strips over joints and nail securely to studs with 8d coated nails. Run a continuous line of plastic cement in all corners with a putty gun. Fit quarter- FIGURE 9. Front wall of chamber with door in place. [14]1 round to corners and nail securely with 8d coated box nails. With a putty gun, run a continuous line of plastic cement on each side of quarter-round and:l" x 2" strips. Door Construction (Figure 9). Make frame of the door of 2" x 3" fir. Allow not more than 1/8-inch clearance for opening on each side, and top and bottom. Brace door frame diagonally with 11/4" x 3" fir. Cover inside with sheet iron, nailing about every 6 inches with 4d nails 1/2 inch from edge of door frame. Put in the rock wool, cover with felt, and then sheet outside with 5/" x 4" ceiling. Attach handles. Make door bars of 2" x 2" oak. FIGURE 10. Inside detail at rear of chamber. [151 Nail a piece of 1" x 2" pine the width of the door on the inside of each bar, so that the door can be pressed tightly against the gasket. Thoroughly clean surface of door stop for the gasket. Fit the gasket carefully according to directions on package. Do not stretch it while fitting. Painting. The outside of the chamber should be given two coats of pearl gray paint. SPIPE Blower Installation. (Figure 10). Install blower on floor at .KNOB ... KO > , W ' 200 w GALV SHEET ,oN rear of chamber. Apply plastic cement around and in holes before the blower is laced and tightened to the floor. Heater Construction. (Figure .11). N Construct heater according to Figure 11. Lumber for the heater is not included in the material list because enough ....... SW scrap lumber usually can be found for its construction. With a coping saw, cut an elliptical Shole in each end piece to fit a 6inch stove pipe. Support the legs and fit stove pipe. heater ,Ru___ / The two sides and top are lined S94wood S HEV. inside with galvanized sheet iron, which is set away from the with porcelain knobs. The six 200-watt bulbs are wired in a series, using 12-guage asbes- "oN I IM)A)woul] ," details of a tos-covered wire. FIGURE 11. Construction heater. Electrical Installations. Install outlet boxes, switches, and fuse box (see Figure 12). Run the Romex cable and ground wire [16] through separate holes in stud. Use plastic cement to make holes gas-tight, both inside and outside of chamber. Solder a lug on the end of ground wire and tighten to ground bus of fuse box. Also, solder a lug on the other end of ground wire inside chamber. SUPPLY ~ls, oldr l tE FUS re-GRUN BOXred f r WRE 6 GA. COPPER 4--GROUND METHYL BROMIDE APPLICATOR 4"COPPER TUBE ESCAPE r LAG SCREW GUARDS THERMOMETER FIGURE 12. |1- Rear view of chamber showing location of switches, outlet boxes, applicator, thermometer, and escape valve. [17] Fasten lug into stud with a screw and solder to sheet iron. Cover with plastic cement. Splice and solder another piece of ground wire to the first piece just outside the fuse box. Run to nearest water pipe and secure end of wire to pipe with a ground clamp. If the water pipe is rusty, file clean before attaching the clamp. Make electrical connections to heater, blower, and switches. Solder all splices. Switches must break the "hot" wire. Connect all sheet iron on inside of chamber by soldering 11/2 x 6-inch strips of sheet iron across the joints, so that all of the sheet metal work completes the ground circuit. Before connecting the electrical supply line, determine the polarity of the circuit and connect accordingly. This is important. Methyl Bromide Applicator (Figure 12). Fasten applicator to outside wall at a suitable height with the screws provided. Drill a hole in the side of outlet of blower for 1 copper tube. Extend tube about 1 inch inside blower outlet and mash end of tube with pliers so that methyl bromide will be sprayed into the air blast. Drill a hole through stud for tube and nail sheet iron to stud around hole with 4d nails. Run tube through wall to applicator and connect. (A union on the inside of the chamber will make the connections easier.) Apply plastic cement to wall around tube both inside and outside of chamber. /4-inch Air Escape. Drill a hole through stud for 1/4-inch pipe nipple. Connect air cock to one end of nipple and pass nipple through [ wall. Apply plastic cement around hole and end of nipple CEMENT COR en with a bushing. MOMTE oPUSHI1l SHEET IRO PLASTIC CEMENT D WL SHEET EIrear RO FIGURE 13. Cross section detail of thermometer installation. Thermometer Installation. (Figure 13). The thermometer is installed about 6 inches from the floor in one corner at the of the chamber where the sheet iron is supported with T & G sheeting as shown in Figure [18] 8. Drill a 1-inch hole through inside wall only. If carefully centered, a 3/-inch hole will allow passage of the thermometer through outside wall. Screw 3/4-inch pipe bushing into 1-inch hole tightly against sheet iron. Drill a No. 4 cork stopper to fit the thermometer snugly. Adjust cork to proper place on thermometer so that 55 to 60 degrees of the scale can be read on the outside of the chamber. Pass the thermometer through wall and screw cork tightly into bushing. Cover cork and bushing with plastic cement. Screw lag screws into outside wall to serve as guards. Build a frame of scrap lumber and cover with 1/-inch mesh hardware cloth to protect the thermometer bulb on the inside of chamber. Apply plastic cement liberally where frame is nailed to floor. It is a good idea to build wooden box covers out of Slumber and fit with hinges and hasps, to cover both the thermometer and methyl bromide applicator when not in use. 1-inch False Floor (Figures 7 and 10). Use 1 x 3-inch pieces for lengthwise members and I x 2-inch material for the spaced cross members. Support on 2 x 4 x 4-inch blocks set on edge. Make the false floor in two sections, so that it can be removed for cleaning the chamber. Final Finishing. Cover nail heads on sheet iron with spots of plastic cement. OPERATION o CHAMBER Before the chamber is used, and at least once a year thereafter, it should be tested for leaks by an inspector or some person familiar with the method of testing. A kerosene manometer', Figure 14, designed for a reading of 50 millimeters, is used for this purpose. The manometer is attached to the air vent cock with a suitable hose. Air pressure is introduced into the chamber until a reading of 50 millimeters is obtained on the manometer. The air pump is then shut off and the time required 1 The authors are indebted to Randall Latta, U. S. Bureau of Entomology and Plant Quarantine, for suggesting this method of testing chambers for leaks. [191 for the kerosene to fall from 50 to 5 millimeters is noted. If the time is less than one-half minute, the chamber is too leakv for use. One minute or more will be required for the kerosene to fall to 5 millimeters if the chamber is in good condition. A tire pump that operates in a spark plug hole of an autos. obile xill provide sufficient 1 ressure for a 200-cubic foot chamber. The air is introduced s Iiv disconnecting the tube from the methyl bromide applicator and connecting the hose from the pump to this tube. FIGURE 14. Manometer used for testing chamber for leaks. meth) 1 bromide is introduced If the chamber is leaky, and an effort is made to locate the leak with a halide leak detector, which may be obtained at a refrigerator service shop. Loading. The floor of the chamber is sprinkled with water before loading. Plants growing in pots or dug B & B can be fumigated as they are. Bare-rooted plants should be placed in flats or open crates and the roots protected xith moist sand or soil. It is better to cover the roots and then sprinkle the soil or sand. Care should be taken that the foliage is not covered. The plants should not be packed tightly together. freely exposed to the gas. They must be Fumigation. Methyl bromide is poisonous to all animal life, and, since there is no warning odor, it must be used with care and intelligence. It is rapidly dissipated in the open air, however, and there is little danger unless a person is confined with the gas. Breathing the fumes should be avoided, and the chamber should never be entered until properly xentilated. [20] When the chamber is loaded, the door is put in place and is tightened against the gasket with the six door nuts. The air cock is opened and the blower is turned on. After the blower has been running for. a few minutes, the temperature is noted. If the temperature is 600 F. or above, the blower is run for 30 minutes, after which the air cock is closed. The temperature is again noted. The dosage of methyl bromide in cubic centimeters and the exposure at the particular temperature are given in Table 1. The gas is then introduced into the chamber. If the initial temperature inside the chamber is below 60 degrees F., it will be necessary to turn on the heater and heat the load until it will remain at 60 or above after the heater is turned off. In the winter, heating the chamber may require an hour or two. It is essential that the plants, as well as the air inside the chamber, are warmed to 60 or above. Dosages have been worked out for an exposure of 2/ hours for temperatures ranging from 60 to 80 ° F., and for an exposure of 11/2 hours for temperatures ranging from 81 to 1000 F. The blower should be allowed to run throughout the entire exposure period. Sometimes during warm weather, the motor that operates the blower may generate sufficient heat to raise the temperature inside the chamber. If after gassing the temperature goes up more than 2 degrees on this account, the blower should be turned off. Successful fumigation is dependent on attention to details. A notebook should be provided for recording the fumigation data. It is best to introduce the gas either on the hour or half hour for ease in keeping records. The time the gas is introduced, temperature, dosage, and the opening time should be recorded in the notebook, so that there will be no doubt about when the chamber should be opened. At the end of the fumigation period, the blower is shut off. The door nuts and the bars are taken off and the door removed. The operator should get away from the door opening quickly. The blower is again turned on and the chamber is aerated for at least 15 minutes before starting to unload. Keep the plants in dense shade for at least 24 hours after fumigation to avoid burning. [21] Fumigation Effective Against Many Pests. Fumigation with methyl bromide, using the dosages and exposures given in Table 1, probably will destroy all insects and mites and their eggs, infesting the wood and foliage of plants. Fumigation at atmospheric pressure (that is, in this type of chamber) is not completely effective against certain soil-infesting insects. Fumigation of Azaleas. Most varieties of azaleas can be fumigated with methyl bromide. A few varieties cannot be fumigated because of their susceptibility to the gas. Among these are Coral Bell and Salmon Beauty. Rooted azalea cuttings can be successfully fumigated for the control of red spider and thrips if the cuttings are heeled in flats of moist sand. In fumigating cuttings, it is recommended that the 90 per cent dosage be used. Fumigation of Camellias. Several hundred varieties of camel- lias have been fumigated experimentally and commercially. None has been found susceptible to injury. Although they may be fumigated any season of the year, it isbetter to fumigate during the inactive or winter months. Open flowers will be damaged, but tight buds will not. Small plants with new growth should not be fumigated until the foliage has hardened. Camellia cuttings, rooted cuttings, and scion wood for grafting have been successfully fumigated. In fumigating cuttings, it is recommended that the 90 per cent dosage be used. Cuttings should not be wet before fumigating. The fumigation of rooted cuttings in flats of moist sand has become routine in some nurseries. Many Kinds of Plants Can be Fumigated. Methyl bromide fumigation is adapted to a wide variety of plants. However, some plants are susceptible to methyl bromide injury and their susceptibility can be determined only by trial. In general, plants are least susceptible to injury when they are not actively growing. Plants that have been fumigated experimentally to determine their reaction to methyl bromide are given in the lists, pages 23-24. [22 1 Table 1. Recommended Dosages of Methyl Bromide for a 200=Cubic Foot Chamber For exposure of 21/2 hours For exposure of 1 1/2 hours Temperature Degrees F. Cubic centimeters for 200 cubic feet Normal 90 per cent dosage dosage 168 161 155 149 143 137 132 127 122 117 112 108 104 99 96 92 88 85 81 78 151 145 139 134 129 123 119 114 110 105 101 97 94 89 86 83 79 76 73 70 Temperature Degrees F. 60 61 62 63 64 Cubic centimeters for 200 cubic feet Normal 90 per cent dosage dosage 193 187 181 176 171 165 160 155 151 147 142 138 133 129 126 122 118 115 111 108 105 174 168 163 158 154 148 144 139 136 132 128 124 120 116 113 110 106 103 100 97 94 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Plants Not Injured by Methyl Bromide Fumigation Acuba japonica Berberis atrocarpa Berberis thunbergi atropurpurea Berberis sargenti Buxus japonica Buxus sempervirens Buxus harlandi Callistemon Cleyera japonica Cydonia japonica Cedrus deodara Cunninglamia lanceolata Eurya japonica Feijoa sellowiana [23] Gardenia florida Gardenia mystery Gardenia radicans Ilex cassine Ilex cassine myrtifolia Ilex crenata microphylla Ilex crenata bullata Ilex crenata rotundifolia Ilex cornuta burfordi Ilex cornuta femina Ilex opaca femina Jasminum floridum Jasminum primulinum J uniperus chinensis albo-variegata Juniperus chinensis densa glauca Juniperus chinensis pfitzeriana Juniperus communis Juniperus excelsa stricta Juniperus sabina Juniperus sabina vonehron Laurocerasus caroliniana Laurus officinale Ligustrum ciliatum variegatum Ligustrum coriaceum Ligustrum japonicum Ligustrum lucidum compactum Ligustrum-lucidum pyramidalis Ligustrum lucidum repandens Liriope muscari densiflora Liriope muscari variegata Magnolia fuscata Magnolia glauca Mahonia bealei Mahonia fortunei Malpighia glabra Mellitia japonica Nandina domestica Ophiopogon japonica Osmanthus americanus Osmanthus fortunei Osmanthus fragrans Osmanthus, fragrans aurea Photinia glabra Photinia serrulata Pittosporum tobira Pyracantha coccinea lalandi Podocarpus sinensis Retinospora ericoides Retinospora pisifera filifera aurea Thuja orientalis aurea conspicula Thuja orientalis nana Thuja orientalis bakeri Viburnum suspensum Viburnum tinus Plants Partially or Completely Defoliated But Not Killed by Methyl Bromide Fumigation Abelia grandiflora Gotoneaster francheti Elaeagnus pungens Elaeagnus pungens fruitlandi Elaeagnus pungens aureo-maculata Ligustrum quihoui Ligustrum quihoui pendulum Magnolia grandiflora Viburnum macrophyllum Viburnum odoratissimum Spiraea reevesiana J uniperus chinensis sargenti Plants Too Seriously Injured by Methyl Bromide to be Fumigated Camellia theae Pyracantha formosana (hard to Juniperus chinensis japonica Juniperus communis depressa plumosa transplant) Pyracantha yunnanensis (hard to transplant) Juniperus chinensis Juniperus japonica oblonga Retinospora femina pisifera fiifera aurea pisifera plumosa aurea Retinospora (Sylvestris)