Bordeaux Mixture as Protective Paint for Apple Trees
When it comes to protecting apple trees from various fungal diseases, one of the most time-honored and traditional methods is the application of Bordeaux mixture. This copper-based fungicide has been used by gardeners and orchardists for well over a century, thanks to its effectiveness in preventing and controlling infections such as apple scab, fire blight, and powdery mildew.
Understanding Bordeaux Mixture
Bordeaux mixture is a combination of copper sulfate, hydrated lime, and water. It is named after the Bordeaux region in France, where it was initially used to control downy mildew in vineyards. The mixture acts as a protective paint, adhering to the trees and providing a barrier against invading pathogens. Its distinctive blue-green color, when applied, also makes it easy for growers to see which parts of the tree have been treated.
Application on Apple Trees
The key to the effective use of Bordeaux mixture on apple trees lies in the timing and method of application. For optimal results, it should be applied at specific times during the tree’s growth cycle. Here are some guidelines for applying Bordeaux mixture:
1. Dormant Season: Apply a Bordeaux mixture during the tree’s dormant period (late winter to early spring before bud break) to target overwintering fungal spores. This application, known as a Bordeaux dormant spray, often uses a higher concentration of copper sulfate, typically in a 4-4-100 (copper sulfate-lime-water) ratio.
2. Spring Application: Additional applications should be made during the spring as new leaves and blossoms appear. Reapplication may be necessary every 7 to 10 days, especially if wet weather prevails, to protect new growth.
3. Post-Harvest: After harvesting the fruit, a lower concentration (such as 1-1-100) Bordeaux mixture can be applied to protect against late-season fungal diseases.
Preparing and Applying Bordeaux Mixture
To prepare Bordeaux mixture:
1. Dissolve copper sulfate in one-half of the required water quantity.
2. In a separate container, create a lime suspension with the hydrated lime and the remaining water.
3. Slowly add the lime suspension to the dissolved copper sulfate, constantly stirring to prevent the ingredients from settling.
4. Strain the mixture to remove any lumps that could clog the sprayer.
5. Apply immediately after preparation to prevent the mixture from settling or becoming less effective.
When applying the Bordeaux mixture:
– Use protective clothing, gloves, and eye protection, as the mixture can irritate skin and eyes.
– Apply using a sprayer that can provide thorough coverage, reaching all parts of the tree, including the undersides of the leaves and branches.
– Avoid application when temperatures are expected to exceed 85°F (29°C), as this can result in plant damage or burn.
– Do not apply the mixture close to harvest time to avoid copper residues on the fruit.
– Be mindful of environmental impacts, as excess copper can accumulate in the soil.
The Bordeaux mixture, when used responsibly and at the appropriate times, can be an excellent tool for organic and conventional growers alike to protect apple trees from various diseases. Always ensure that you adhere to local agricultural regulations and best practices when using any fungicide.