Dealing with American Foul-brood

New Zealand Journal of Agriculture, Volume 81, Issue 6, 15 December 1950, Page 558

Dealing with American Foul-brood

Seasonal Notes for the Domestic Beekeeper A HEALTHY honey bee population spread over pasture lands and fruit-growing and seed-producing areas is most important to New Zealand’s economy. It can be achieved by careful breeding of desirable bee stocks and correct methods of apiary management, including strict measures in dealing with any colonies infected with disease. This article by the Horticulture Division discusses the eradication of American foul-brood.

AS the careful beekeeper cannot take precautions against a careless neighbour who neglects his bees, the State gives him legal protection. Unfortunately honey bees are subject to a number of diseases and pests including those which attack the brood and those which affect the adult bee. However, American foul-brood (Bacillus larvae), which was introduced into New Zealand with imported bees many years ago, is the- most serious disease of bees in New Zealand. Until recently beekeepers have been allowed to treat infected colonies under certain circumstances, but experience has shown conclusively that the shaking method of treatment to save infected colonies has been unsuccessful in eradicating the trouble. In future beekeepers will be required to destroy the contents of diseased hives found by Apiary Inspectors and to sterilise thoroughly any remaining hive equipment by approved methods. It is not considered necessary to burn good apiary equipment such as hive boxes, lids, and floor boards provided they are sterilised thoroughly. Eradication of Foul-brood The measures that are necessary to eradicate foul-brood are set out here for the guidance of beekeepers, who should make periodical , inspection of their hives during the breeding season and deal promptly with any brood troubles found. Destruction of Diseased Bees The safest time of the day to destroy diseased hives of bees is in the late evening or during wet weather when there is no likelihood of bees flying during the day. The most common method of killing bees preparatory to burning hives is to gas them with calcium cyanide. One or 2 tablespoons of the powder should be scattered inside the hive on the floor board or spread quickly on a piece of damp cardboard and pushed into the hive entrance. The beekeeper must stand on the windward side and should not allow the powder to come in contact with" his fingers or body. Another method is to lift the hive cover, drop the powder between the combs, and replace the cover immediately. In a very short time the bees will all be dead. Calcium cyanide is a deadly poison and is used at the operator’s own risk. Distributors of the chemical supply full directions for its use under all circumstances with each package. These directions should be read carefully and followed meticulously.

An alternative method is to block the hive entrance carefully after making certain that the hive is otherwise bee-tight, raise the hive lid, and pour petrol (1 or 2 cups according to the size of the. hive) inside over the bees and combs. The hive should be left closed and undisturbed until the vaporised petrol has killed the bees. Care should be taken when the material to be burnt is ignited, as the fumes will create a small explosion. Burning Diseased Bees and Combs The first step in burning diseased hives is to dig a hole about 3ft. or more in diameter (according to the amount of material to be dealt with) and Ift. to 2ft. deep close to the affected hives. Part of the hole should be made deep enough to take any liquid honey that may escape the fire and to allow the honey to be buried finally well below digging or ploughing level. Two iron bars, old pipes, or heavy timber placed across the top of the hole are helpful in keeping the fire from collapsing and allowing any honey that escapes to run away without choking the fire. Place a liberal amount of dry twigs or any fine, dry wood in and above the hole to give the fire a good start. Carry the diseased hives to the pit, taking care not to spill any of the contents on the ground. If a hole (approximately 18in. deep) is made large enough to allow ample ventilation the fire may be started on the bottom of the hole at one end as illustrated. The dead bees should be shaken on to the stack together with the hive mats and any worthless woodwork. The fire should then be started and frames free of honey stacked in the centre, as they will burn easily. When the fire has a good hold add additional combs containing any brood and honey around the edges of the fire, which should be kept well ventilated, and allow any melting material to run to the deepest part of the pit. When all the material is burnt the surface of the ground around the pit to a depth of 1 or 2in. should be removed with a spade and thrown into the pit to avoid the danger of leaving any dead bees or other infected material accidentally, dropped while burning the frames and combs. The pit should then be refilled with earth, and all salvaged hive equipment removed immediately to a safe place for sterilising. , Disinfection of Hive Parts and Appliances All salvaged material taken from diseased colonies should be sterilised as soon as possible after the destruction of the bees and combs. Any brace combs or propolis and refuse

from bottom boards should be scraped off and carefully collected and burnt. Metal rabbets attached to the hive boxes should be removed and sterilised or. burnt. The interior surfaces of hive boxes, lids, and bottom boards should be scorched with a painter’s blowlamp. Scorching should be thorough but not to the extent of charring the woodwork. Special care should be taken to see that all cracks and corners are scorched by the flame, as otherwise the treatment may not be successful. Boiling Equipment in Wood Oil Wood oil is a light oil with a low boiling point. If heated to the stage at which vapour begins to come off, it will be at a temperature of approximately 212 degrees F. At this temperature it can be used to sterilise equipment, which should be immersed in it for a minimum of 15 minutes. Where oils are used it is preferable that operations should be performed outside and care should be taken to select a container which will allow plenty of room for the expansion of the oil when heated, so that it will not spill and be ignited by the fire. Boiling equipment in paraffin wax is effective, but is tricky. Details of this method may be obtained from Apiary Instructors. Queen excluders and feeders which cannot be treated with a blowlamp should be boiled for 15 minutes in a caustic soda solution Gib. of caustic soda to 10 gallons of water), but the operator should take care not to get the solution on his face or hands. Where there is no beeswax or propolis adhering to the equipment a weaker solution (4oz. of caustic soda to 10 gallons of water) should be used.

If a hive tool has been used in the operations, it should be well sterilised by fire before being used again.