Sprays for Lemon Trees

Summertime wouldn’t be the same without tangy lemonade at your barbecues. Even if you rent your home, you can grow a lemon tree in a large container and reap the benefits of this tasty, nutritious fruit. But all good things have their price: diseases sometimes attack lemons and other citrus trees. Fungal, bacterial and viral diseases can slow fruit production and cause your tree to suffer. Help is just a spray bottle away.

Sulfur and Copper Sulfate Spray

Several fungal diseases can afflict lemon trees. They include powdery mildew and anthracnose. Sulfur spray is effective in controlling powdery mildew, but you must begin spraying with it before the disease occurs, according to the University of California at Davis. It causes a fuzzy gray or white substance on the leaves. Sulfur is an organic substance, but copper sulfate spray--the remedy for anthracnose--is a chemical product. This disease causes a lemon tree’s leaves to drop and can cause black spots on the fruit. Old Bridge Chemicals, a manufacturer of the sprays, advises that copper sulfate can cause “substantial” injury to the eyes if contact is made. They give other cautions as well, so if you choose to use a copper sulfate product, be sure to follow label instructions.

Copper Oxychloride

The fungal disease called "scab" causes rough bumps on lemon tree leaves and fruit, says Australian website Our Brisbane. You can control this disease with copper oxychloride spray, which is available at nurseries. This product is a chemical fungicide and can cause the skin, eyes and respiratory system to become irritated, as well as being responsible for nausea, vomiting and stomach pain when poisoning occurs, according to online resource Pesticide Info. This site goes on to explain that severe poisoning can cause the collapse of the circulatory system and shock.

Liquid Copper Fungicide

You’ll know if your lemon tree has contracted the greasy spot fungal disease if it develops yellow or brown blisters on the bottom of its leaves. Tree Help.com reports that the fungal disease melanose usually occurs on grapefruit trees, but it can attack lemons as well, especially younger trees. It causes the rind of the fruit to look as if it has scabs. Liquid copper fungicide is effective in controlling both the greasy spot and melanose fungal diseases. It is considered organic, according to the Planet Natural website, which also states it will not burn your tree. However, certain precautions exist, such as irritation to the respiratory system, so be sure to follow label instructions if you use this product.

Insecticidal Soap

Aphids and scale are common insect pests on lemon trees. Not only do they suck the plant’s juices, they can contribute to the citrus tristeza virus. Ants carry aphids to the tree, to harvest "honeydew," a sticky substance excreted by aphids. Although the ants do not directly harm your tree, the insects they bring feed on and weaken the tree and their honeydew can cause diseases such as powdery mildew. Keep a close watch for ants and use a barrier product around the tree’s trunk. If you miss the first signs of this insect and they succeed in introducing harmful insects, spray your tree with organic insecticidal soap and keep spraying every day or two until you see no further signs of the invaders.

Keywords: lemon trees, citrus diseases, sulfur fungicide copper

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, GardenGuides and eHow. She earned her B.A. at UCSB and her M.A. from San Jose State University.