Description of the Pest
Nematodes are microscopic roundworms that live in diverse habitats. Plant parasitic nematodes live in soil and plant tissues and feed on plants by puncturing and sucking the cell contents with a spearlike mouthpart called a stylet.
Little information is available on damage to figs resulting from a nematode infestation. Lesion, root-knot, and dagger nematodes are known to cause reduction in growth and yield. The trees are likely to be more susceptible to temperature and water stress.
The symptoms described below are indicative of a nematode problem, but are not diagnostic as they could result from other causes as well. Lesion nematode infested trees may appear stunted with very few feeder roots. The roots may have reddish brown lesions that eventually turn dark. Root-knot nematode infested trees are also likely to have reduced growth and appear stunted. The roots have distinctive swellings, called galls. Dagger nematode causes gall formation on root tips.
If the symptoms described above are present and no cause is evident, sample the orchard to determine if lesion, root-knot, dagger, or other plant parasitic nematodes are present.
If nematode species have not previously been identified, take soil samples and send then to a diagnostic laboratory for identification. Divide the field into sampling blocks of not more than five acres each that are representative of cropping history, crop injury, or soil texture. Within each block, take several subsamples randomly from the frequently wetted zones at the edge of the tree canopy. Take samples from within the root zone (6 to 36 inch depth) and include some feeder roots when possible. Mix the subsamples thoroughly and make a composite sample of about 1 quart (1 liter) for each block. Place the samples in separate plastic bags, seal them and place a label on the outside with your name, address, location, and the current/previous crop and the crop you intend to grow. Keep samples cool (do not freeze), and transport as soon as possible to a diagnostic laboratory. Contact your farm advisor for more details about sampling, to help you find a laboratory for extracting and identifying nematodes, and for help in interpreting sample results.
Nematode problems on fig in California have not been extensively studied, so no specific treatment recommendations are made. However, trees planted in fumigated soil are known to grow considerably better than trees planted in nonfumigated soil. Metam sodium* (Vapam, Soil Prep) and 1,3-dichloropropene* (Telone II) are available for preplant use on figs. Fumigants such as metam sodium* (Vapam, Soil Prep) and 1,3-dichloropropene* (Telone II) are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available.
* Permit required from county agricultural commissioner for purchase or use.