Lime sulphur spray is both a fungicide and pesticide that gardeners have been using since the mid-19th century. This strong chemical is yellowish orange and has an extremely pungent odour. It can be used on various types of fruit trees, shrubs and shade trees. Gardeners use lime sulphur to eliminate insects including scale, mites and borers. Moreover, it can effectively control certain plant diseases such as leaf blotch, nectria canker, anthracnose, apple rust, peach leaf curl, black spot and maple gall. Because of its high toxicity, special handling and storage are required.
Mix lime sulphur with water in a pressure sprayer. The amounts of lime sulphur and water should be indicated on the product label, depending on the purpose of use. For example, if you would like to prevent black spot on apple trees, you have to apply 9 1/2 to 13 oz. of lime sulphur per gallon of water. But if you want to control leaf blotch, the ratio will be 70.9gr. of lime sulphur per gallon of water.
Avoid inhaling or coming into contact with the vapour by wearing coveralls over long-sleeved shirts, long trousers, boots, hat, waterproof gloves and goggles or a face shield.
Apply lime sulphur when it is not windy. If you can't avoid it, spray in the wind direction so that the chemicals will not drift to susceptible animals, humans or other plants. Keep spraying until all the leaves are wet. The ideal time of the day to apply lime sulphur is either morning or late afternoon when the climate is not too hot.
Don't enter the treated areas or touch the treated plants without protective clothing until the foliage is completely dry.
Store the spray container in an upright position in a cool and dry area away from children and animals. If the container is empty, do not reuse it. Wrap it in many layers of newspaper and dispose in trash.
The best time to use lime sulphur on dormant fruit trees, such as apple and cherry trees, is in late January when temperatures are above freezing or around early spring right before the buds swell. Once the growth starts, repeated applications might be necessary, depending on what type of plants you are cultivating. For example, rose shrubs may need to be treated every 10 to 15 days, whereas peach trees only need to be sprayed twice, once before and once after blooming.
Don't use lime sulphur spray on evergreens, apricots and rhododendrons, as it might burn the fruits and leaves. Don't apply oil with or soon after lime sulphur application, especially in the summer. Wait at least 3 weeks. Don't apply lime sulphur on a hot day when temperatures exceed 85 degrees Fahrenheit; it might destroy the fruits and foliage.