Many types of fungi serve a valuable purpose in the garden.  They contribute to healthy soil and they have a symbiotic relationship with plants that allows both types of organisms to thrive.  However, some fungi are harmful in the garden.  These destructive types, called pathogens, invade healthy plant tissue, weakening the plant and slowly killing it.  In fact, the most prevalent cause of plant disease is harmful fungi.  One fungal condition that you should know about is botrytis, commonly referred to as gray mold.  Here are some tips on identifying and controlling this disease.

Gray mold can strike a wide variety of flowers, vegetables, and fruits.  It is widely seen in cool and damp climates.  The disease is characterized by a tan, gray-brown, or gray fuzzy mold that shows up on plant leaves and stems.  There may be brown blotches surrounding the moldy areas.  Fruit and vegetables are also susceptible, often exhibiting tan blotches that turn into rough gray mold.  The fungus usually starts on old plant material or fruit and spreads to healthy growing plants, causing the tissue to rot.  The spores are spread by the wind and by splashing water.

Many new varieties of ornamental plants and vegetables are resistant to fungal infections.  Choose these cultivars, where possible, to help keep your garden disease-free.  In addition, planting different flowers, vegetables, and herbs next to each other instead of grouping plants of one type together is a proven strategy for inhibiting the occurrence and spread of fungal disease.

Because gray mold loves shady, moist, crowded conditions, be sure to give individual plants enough space for good air circulation and avoid overcrowding.  Prune inside branches as necessary to allow for air movement.  Keep foliage and blossoms dry when watering by using a soaker hose or a watering can with a long spout.  Do your watering early in the morning so the plants and soil can dry out during the day.  Avoid working with wet plants to minimize the chance of spreading fungal spores throughout the garden.

Sanitizing affected plants is critically important and should be done at the first sign of gray mold, before you take any further steps.  To sanitize means to remove dead or visibly infected leaves, stems, branches, fruit, or flowers.  The goal is to get rid of infected tissue, which is a source of spores that are easily transferred through the air or by physical contact.  Be very thorough in pruning or picking off affected parts of sick plants.  Don’t handle other plants while you are doing this or you can unwittingly spread the disease.  If you sanitize quickly, you may be able to stop the fungus from destroying the entire plant.  Infected plant material should be disposed of in the garbage.  Alternatively it may be burned to ashes and then composted.  Never put it directly on a compost pile or into a green waste collection program.

A dusting of sulfur on sick plants may help to control the mold.  Garlic has anti-fungal properties so you may also want to try a simple garlic spray.  You can make it yourself by crushing a bulb of garlic and putting it in a pan with a quart of water.  Bring the mixture to a boil, turn off the heat, and let it cool.  Strain it to remove the garlic.  Put the liquid in a spray bottle and spray affected plants, repeating as necessary.

A fungal disease such as gray mold can easily damage ornamental plantings or reduce the seasonal food harvest if you allow it to gain a foothold in the garden.  However, you can keep your plants from falling victim to gray mold by taking simple precautions.  Discourage the growth of fungi by choosing resistant cultivars and keeping plants dry.  Make a point to inspect all your plants often and remove any material that shows signs of infection.  You can be sure that the effort you put into keeping the garden disease-free will pay off in the end.