Preparation of Spray Solutions
The insecticides registered for control of bark beetles of southern pines are all formulated as emulsifiable concentrates and readily mix with water.
Read the label! Labels always carry instructions for mixing certain volumes of finished spray. However, it is convenient to know the formula for dilution of a concentrate so that any amount of finished spray may be prepared. Lindane is normally formulated at 20 percent active ingredient but the label should be checked before mixing. Suminithion 8E contains 8 pounds of fenitrothion per gallon. Dursban 4E contains 4 pounds of chlorpyrifos per gallon. The ratio of water to insecticide formulation must be calculated to achieve the proper dilution for a finished spray.
When the active ingredient of a formulation is specified by percent (e.g. Lindane 20%) then the following formula is used.
(Desired Percent of finished spray) x (Desired Amount of
(Percent Concentration of formulation)
The following is an example of this:
To prepare 100 gallons of 0.5% lindane spray:
.5% x 100 gallons =
Add 2.5 gallons of 20% lindane EC to 97.5 gallons of water.
If the undiluted formulation is given as pounds per active ingredient per gallon (e.g. Sumithion 8E) then use the following formula:
(Desired percent of (Desired amount of (weight of finished spray)
x finished spray) x water per gallon)
(pounds of active ingredient per gallon x 100
The following are examples:
To prepare 60 gallons of 2% chlorpyrifos spray:
2% x 60 gallons x 8.34 lbs./gallon = 2.5 gallons
4 lbs./gallon x 100
Add 2.5 gallons of Dursban 4E to 57.5 gallons of water.
To prepare 50 gallons of 1% fenitrothion spray:
1% x 50 gallons x 8.34 lbs./gallon = .53 gallons
8 lbs./gallon x 100
Add .53 gallons of Sumithion 8E to 49.47 gallons of water.
When mixing, it is essential that you measure very carefully. If concentrates are being added to a large tank, be sure you know how much water is in the tank. Accurate measurement of pesticide is useless if you do not accurately measure the amount of water (the carrier) that will be used to dilute the concentrate.
Before you begin any application you should be sure that the concentrate has been thoroughly mixed with the water carrier.
Protective clothing and other safety equipment should be worn during all phases of preparation and application of toxicants for bark beetle control. Persons who handle or apply insecticides should wear the following:
A good respirator with replaceable filters.
Eye protection. Safety glasses or goggles should be constructed in such a way that they prevent entry of material from the sides.
Respirators are available which have a face shield for eye protection and respirator incorporated into one unit (Fig. 12).
A hat, preferably a hard hat with a wide brim.
Coveralls or outer garments which can be removed easily when contaminated.
Fig. 13 shows an applicator wearing the proper equipment to spray for bark beetle control.
|Fig. 12. Combination respirator/face shield (center)|
|Fig. 13. Applicator wearing safety gear|
Application of Finished Spray
Once you have selected the chemicals and made the proper dilution you are ready to apply the finished spray.
Preventive Treatment - If you determine that trees need protection only from the BTB, then the trees you have selected and marked will need to be sprayed only on the basal 10 ft. Spray until the bark is thoroughly wet and be sure to spray around exposed roots at the base. It may be necessary to rake some debris away from the roots for good coverage.
Prevention of Ips spp. attack requires that trees are sprayed well up into the live crown, preferably to the area where the stem diameter is about 4 inches. Spray until the bark is wet over the entire bole.
SPB attacks can be prevented by applications similar to those for Ips beetles. However, it has been shown (Beriford, et al. 1982) that SPB attacks can be prevented by spraying only the top half of trees. This approach probably works because most initial SPB attacks occur above midbole. Also, a considerable quantity of spray runs down bark crevices onto the lower bole and SPBs normally attack in bark crevices.
Remedial Treatment - Identify and mark only those trees which still contain some life stage of bark beetles (adults, larvae, pupae).
If possible, fell trees infested with Ips spp. or southern pine beetle before spraying. Trees successfully attacked by these species always die and usually must be cut anyway. Low volume and low pressure sprayers may be used on felled trees; they require much less insecticide and nontarget contamination is minimized. Spray the entire infested area on each tree. This may be only 6-10 feet for BTB attacks. Felled trees should be cut and turned for good coverage (Fig.14). Proper coverage on standing trees infested with SPBs or Ips requires high pressure and high volume sprayers.
|Fig. 14. Spraying and turning felled trees|
Selection of Spray Equipment
Spraying felled trees or treating for BTB's - When only the basal portion of trees are sprayed for BTB or when felled trees are sprayed for remedial control of Ips spp. and SPB, small "backpack" or "hudson type" sprayers may be used. These are especially convenient when only a few trees require treatment. For similar treatments on large numbers of trees, low pressure and low volume power sprayers may be more convenient.
Spraying Standing Trees - To effectively spray standing trees, especially large ornamental trees, specialized equipment is required. Sprayers for this task must deliver high volumes of liquid at high pressures. These sprayers must be capable of delivering a solid stream into the crowns of trees to be treated. On large trees, the spray must sometimes reach 70-80 feet.
During all phases of preparation, application and cleanup of chemicals for bark beetle control, be sure to observe all rules of pesticide safety. These rules are:
Read the label - In addition to providing mixing instructions, the label also contains information on dealing with accidental poisoning. Remember, different insecticides may require different tactics.
Wear protective equipment - The proper equipment should be worn whenever insecticides are handled, not just when actual applications are made. Insecticides are more likely to cause poisoning as concentrates than after dilution.
Avoid contamination of nontarget areas - Prevent direct application or drift into areas frequented by people and pets. Do not apply toxicants on or near lakes and streams. Do not spray where honeybee colonies or edible crops could be contaminated.
Clean and store equipment properly - Sprayers and holding tanks should be cleaned after use. Care must be taken to prevent pesticides from getting into streams, lakes or wells. Empty containers should be punctured and buried in approved landfills.
Store chemicals properly - Insecticides should be kept in their original containers and stored in a well ventilated secure area.