It is capable of living without water and tolerates desiccation for several years. The stubby root nematode lives in the soil and feeds on the roots. Lesion nematode, Pratylenchus penetrans, has been reported on onions and garlic in other states where it suppresses the growth and yield of these crops. While this nematode is found in California, it has not been found to cause problems on onions or garlic. The stem and bulb nematode penetrates the germinating clove and destroys tissue as it moves through seeking food.
Nematodes sucking the cell contents and salivary secretions cause the cells to collapse.
Root knot nematodes can cause stunting and reduce a stand. Stubby root nematode causes stunting of plants. The symptoms described below may be an indication of a nematode problem, but are not diagnostic as they could result from other causes as well. Under moist conditions, secondary invaders such as bacteria, fungi, and onion maggots induce soft rot and decay of the bulbs. Root knot infestation can cause stunting, uneven stands of plants, and produces characteristic galls on roots.