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Need helpful guide on how to control anthracnose on guava fruit during wet weather. Even this disease is out of control after using fungicides. I am using fungicides shortly before flowering.

Is there any organic way to control this disease?
How, when to use fungicides to control anthracnose?

It's very difficult, organic or not.

Best for any fungal disease is prevention: Fungal diseases do best in conditions of poor air circulation, damp/ humid. Space your plants widely apart to maximize air circulation and increase sunlight. Don't let leaves or plant litter that could contain spores stay around. Prune in winter for more air circulation. Be careful with pruners - wipe with alcohol between plants, so you aren't spreading disease. Water only the soil, not the plant, and mulch well to reduce soil splashing up (and conserve moisture, suppress weeds). Apply organic fungicides early (before any sign of disease) and often. They work much better as prevention than cure. This would include baking soda solution, hydrogen peroxide, diluted milk. Not all organic gardeners would use copper sulphate, but some would.

Once the disease has really taken hold there is no cure. Harden your heart and remove the plant early before it spreads disease to others.

To improve air circulation in the tree, prune the tree regularly to open it up and apply the fungicide before the rainy season starts. Spores will carry over in debris and guavas are messy trees so it is important to rake up all of the fruit and leaf litter and bury or burn it regularly. Anthracnose will also attack the leaves and not just the fruit.

The best time to prune the guava is one or two months after harvest. Guavas will sucker so keep cutting off the suckers.

Seems a lot of monitoring and working required to prevent Guava from anthracnose disease. How to apply hydrogen peroxide on trees? Is it strong enough to treat disease ?

hydrogen peroxide from the drugstore is a 3% solution, so you can put it straight in a sprayer. I don't know how big your guava tree is and I have no experience spraying trees. I assume you climb the tree with your hose and hose end sprayer and spray from the top and then you stand under it and spray from the bottom.

I don't know anything about growing guava, which is tropical and doesn't survive where I am, or about guava anthracnose, but I am familiar with dogwood anthracnose, which is wiping out the lovely native dogwoods in the eastern half of the country. It is most likely another one of those imported diseases (most likely from China), that appeared suddenly in this country in the 1970's, thanks to globalization.

To avoid the anthracnose, you need to keep your trees in as good shape as possible. Any kind of stress on the tree makes them more vulnerable. And any kind of wound gives an entry point. So you need to manage insects more tightly than you ordinarily would, because insect damage to leaves can be that entry point. Also be careful in pruning sucker, etc not to leave wounds.

THERE IS NO CURE. If a tree has a severe case, it must be removed. If you don't care about being organic, you can try the fungicide propiconazole (see https://www.helpfulgardener.com/forum/vi ... 11&t=57653 midway down the page for information about it). It is a toxic chemical and harmful to honeybees and other beneficial insects and not good for you, especially with repeated exposure. AND it slows or stops the growth of the fungus, preventing further infection and/or invasion of host tissues. It is considered to be fungistatic or growth inhibiting NOT fungicidal or killing. So it still is NOT a cure for badly infected trees.

Yes, with globalization and climate change, life has gotten much more difficult for many crop growers, who now have to contend with new diseases, pests, weeds for which there are no natural controls in the environment.

I don't know about where you live, but guava trees will actually grow wild here. They do get a lot of pests but they are also very prolific. I usually have to cut them because the birds plant the seeds where I don't want them and the wood is hard to cut with a hand saw. They do sucker a lot.

I don't know if peroxide will work. Copper sulfate is recommended for anthracnose on guava.

Cultural controls, I.e., pruning to open up the tree, pruning off infected branches and good sanitation to remove infected leaves, twigs, and fruit are the main ways to control the disease.

Guava fruit here are rarely nice. they get stung by fruit flies, they are easily damaged and bruised and they get diseases but they are so prolific, we just cut out the bad parts and use the rest. Same with mango. Anthrachnose is common especially on very ripe fruit, so if you pick the fruit greener, they look better. Selecting a resistant cultivar helps. It is best to grow your tree from a cutting from a resistant tree instead of from seeds. Otherwise, do the same thing and cut out the bad part. Most guavas here are juiced anyway since they are so seedy.