Diseases & Pests: Many growers have been hit with White Rot that causes black spots and decay on the bulbs. It is easily spread in infected soil and water and is very persistent in the soil. Flooding the bed for 4 weeks in the spring may kill it. Best way to avoid it is not to leave decaying alliums in the ground and by using a strict 4-year rotation.
Companion Planting: Planting garlic near roses will help to repel aphids. Because of its sulphur compounds, it may also help repel whiteflies, Japanese beetles, root maggots, carrot rust fly, and other pests. Garlic, made into a tea, or spray, will act as a systemic pesticide, drawing up into the cells of the plants. It’s a good companion for beets, Brassicas, celery, lettuce, potatoes, strawberries, and tomatoes. Avoid planting it near peas or beans of any kind.