May 28, 2012

Fungus and Wet Weather

We have had a lot of rain over the last three weeks and for the most part it has been somewhat cool, these are ideal conditions for fungus and disease. Though every plant seemed to explode with verdant new growth this year, those new green leaves might not look so healthy in a few weeks. Black spots, yellowing and white powder all indicate disease and fungus, which flourishes in weather like this. If you don’t see problems yet, it’s not too late to prevent an infection. The problem is the water provides perfect conditions for disease-causing fungi to flourish.

Chlorosis, or yellowing of the leaves can also be a result of a pH deficiency in the soil. Cool, wet soil conditions make it worse.  Iron chlorosis causes yellow leaves with green veins. It takes months to push soil pH with either lime or sulfur depending on the nature of the pH problem but a short term solution is a foliar spray. Solve the problem with chelated iron, which helps the plants absorb the essential mineral. Available at nurseries, you mix it with water and spray it on the affected plant.

Thicker isn’t better. Thick, luscious lawns might feel good on the feet, but they’re the perfect breeding ground for fungus. If your lawn is already super thick use a dethatching machine to thin it out and remove inert material which provides ideal breeding ground for fungi.

If you are noticing signs of fungi or disease, often spraying with dormant oil will reduce spreading of the spores. If you’re not so interested in an organic approach, a broad spectrum systemic fungicide, will take care of many types of fungi. If you already have fungus, you should still spray. It won’t get rid of what’s already there, but it will stop spores from spreading. When new leaves come back next year, they’ll be fungus-free.

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