Figs form large, spreading trees that present a rather dramatic presence. The fig itself is a unique fruit that is actually formed from a cluster fleshy flowers, turned outside-in. Figs are prone to a variety of diseases and pests that attack the tree's foliage, bark and roots. The nematode is a particularly difficult pest to control, living in the soil that the plant grows in and affecting its root system.
A nematode is a type of roundworm. Nematodes are some of the most successful creatures on earth, living in a huge range of environments and feeding on a wide range of food sources. Some nematodes live beneath the soil and survive by attacking and feeding on the root systems of plants.
Types of Nematodes
Figs are susceptible to attack from three specific types of roundworms: the Pratylenchus vulnus or the lesion nematode; Meloidogyne incognita and M. javanica also known as the root-knot nematode; and Xiphinema index, commonly called the dagger nematode. These nematodes are microscopic, living within the soil and attacking the root system of fig trees.
The nematodes will feed on the roots of the fig tree. This causes lesions to form. The roots respond by swelling, eventually forming a growth called a gall. Galls on roots inhibit the ability of the plant to absorb water and nutrients from the soil. Consequently, the growth of the affected tree will be retarded.
Galls caused by nematodes are relatively easy to observe when the roots are dug up and examined. The root may also have reddish brown lesions on them. As the attack from the nematodes increases the tree will lose vigor and slowly decline. Premature fruit drop may occur. If nematodes are suspected, soil samples should be taken for microscopic analysis.
Prevention is the best form of management and should be considered carefully when planting figs. Do not obtain suckers from the crown of plants as they may be more likely to be contaminated with nematodes or their eggs. If cuttings or trees are being bought, ensure that the source is reliable. Finally, if a tree has become severely infested with nematodes, the most effective management may be to remove and destroy the tree and treat the soil by fumigation. Planting trees in soil that has been fumigated for nematodes can significantly reduce the risk of infection.