What Causes Tips of Garlic Plants to Turn Yellow Early in the Season?

Rots

• Caused by fungus, rots cause the foliage to yellow and rot the bulb before it has a chance to fully form. Basal rot slowly kills the plant, while white rot causes a much quicker death. White or gray fungal rot may be visible at the base of the foliage, or the foliage may just die back prematurely. Digging up affected plants helps stop the spread to nearby healthy plants, but the garlic should be planted in a new bed the following year to prevent the issue from reoccurring.

Nematodes

• Microscopic worm-like parasites called nematodes infest many soils. They feed on garlic, which leads to yellow foliage and deformed bulbs. Control is preventative; once plants are affected, there is not much that can be done. Keep garlic beds weed-free, as weeds may attract increased nematode activity in the garden bed. Rotate crops each year and avoid planting in beds that have had nematode issues in the past.

Onion Maggot

• The larvae of an insect similar to houseflies, onion maggots feed on immature garlic bulbs. Yellow, dying foliage indicates bulb death causes by maggot infestation. Once infested, the garlic plant dies. In areas where onion maggots are a known problem, cover the bed with a floating row cover to prevent infestation. Dig up infected plants and destroy them to prevent the maggots from spreading to nearby healthy garlic bulbs. Avoid planting in beds that formerly had onions or chives growing in them.

Water Stress

• Too little water causes foliage yellowing and premature dieback. Garlic does not tolerate drought-stress. Water regularly, supplying approximately 1 inch of water a week. Avoid overwatering and soggy soils, as this is as damaging as lack of water.