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Garden rust is one of many plant fungal diseases that can infect flowers and vegetables in warm, humid conditions during the growing season. Chemical fungicides are one of the more toxic conventional plant sprays used to control this disease, but organic gardeners can treat rust with natural cultural controls and sprays.
Identify Garden Plant Rust
Plant rust doesn’t refer to one disease, but rather thousands of species of fungi that can attack landscape trees and plants. In most cases, however, the symptoms are the same: rust-colored or yellow powdery spots on leaves, which harbor fungal spores that spread by wind and rain. Rust infections usually don’t kill affected plants, but can cause leaf drop and stunted growth.
Cedar-apple rust is of particular concern to apple growers. The fungal disease can appear on junipers as brown swellings on the needles, which then grow into hard galls. In the spring the galls swell with the rain and produce long protuberances, which release spores. These spores spread in the wind to infect apples and crabapples, which exhibit rust-colored spots on leaves and fruit. This rust also affects the eastern red cedar, as its name suggests.
Prevent Rust Fungal Diseases
The cultural tips to prevent garden rust are the same good habits that prevent many plant diseases. Gardeners should avoid overhead watering, and use soaker hoses to keep foliage dry. At the least, perform overhead watering early in the morning, so foliage dries quickly. Promote good air circulation by pruning densely planted areas, and by following the spacing recommendations for vegetables and flowers.
Gardeners with junipers in the landscape should watch for the formation of galls, which reveal an infection with cedar-apple rust. Remove the galls before the orange horn formations release disease-spreading spores into the air. Gardeners who wish to grow apple trees in the vicinity of eastern red cedar or juniper trees should choose rust-resistant apple varieties like ‘Liberty,’ ‘Nova Easygro,’ ‘Priscilla,’ or ‘Redfree.’
Baking Soda Garden Spray
The National Sustainable Agriculture Information Service discusses the remedy of baking soda as a natural fungicide for rust, an idea that gardeners have used for more than 80 years. Researchers conclude that using a mix of baking soda with water alone is ineffective. Instead, gardeners must make a solution of 2% baking soda and 1% horticultural oil to leaves when rust is present. Researchers speculate that the efficacy of baking soda to treat fungal disease is a function of fungal cell membrane disruption and unfavorable pH changes.
Source:
University of Missouri Extension
Jamie McIntosh - Jamie has written hundreds of garden articles for the web, and is your guide to Flowers on About.com.
