|Plant nematode problems and their control in the Near East region. (FAO Plant Production and Protection Paper - 144) (1997)|
|Part II: Country reports|
In order to combat the ill-effects of phytonematodes in Jordan, the following is a summary of the measures employed.
In the plant quarantine section of the Jordan agricultural law, prevention of the introduction of certain plant-parasitic nematodes is specifically mentioned. Among these nematodes Globodera rostochiensis, Heterodera schachtii, Meloidogyne spp. and Ditylenchus dipsaci are included. However, at the points of entry there are no reliable laboratories to test plant shipments for nematode presence. Inspectors only look for galling, caused by root-knot nematodes, on the roots of imported plants.
Abu-Gharbieh and Hammou (1977) concluded that susceptible tomato cultivars may escape root-knot nematode infection in the central Jordan Valley by planting during November through December. Earlier plantings must be supplemented by soil fumigation or the use of resistant varieties. Abu-Gharbieh (1982b) showed that neither hoeing nor removal of infested refuse of the previous crops gave significant nematode control in heavily infested soils.
Cultural practices also include the use of crop rotation in which susceptible, resistant and non-host varieties and cultivars are planted in a certain sequence, so that nematode counts remain at non-damaging levels. In this respect, a large number of varieties, cultivars and lines of vegetable crops have been tested in Jordan for their relative susceptibility or resistance to the root-knot nematodes M. javanica and M. incognita.
Addition of Fusarium oxysporum, Aspergillus flavus and Preussia sp., grown on wheat grains, reduced postharvest cyst populations on sugar beet by 81.9, 74.5 and 62.4 percent, respectively. Abu-Laban and Saleh (1992) showed that Paecilomyces lilacinus, F. solani and F. oxysporum formulated on chicken layer manure significantly reduced root-knot nematode galling on tomato roots by 58, 59 and 53 percent, respectively. Naturally occurring fungi that parasitize cyst and root-knot nematodes in Jordanian soils were investigated; the most important fungi found included Verticillium chlamydosporium, Aspergillus flavus, Fusarium oxysporum and Fusarium solani.
Khatoom (1981) showed that preparasitic, second-stage juveniles of Meloidogyne javanica were not detected at the end of the growing season of cucumber in a soil treated with methyl bromide. Abu-Gharbieh (1982b) reported that 75 days of preplanting soil fumigation treatment with DBCP (Nemagon) gave a marked reduction in population densities of the nematode M. javanica and increased tomato yield. However, a 15-day preplanting treatment showed significant nematode control but without significant yield increase, which may suggest a phytotoxic effect on tomato. Investigations also indicate the effectiveness of liquid oxamyl, Di-Trapex and Basamid treatments.
One of the most recent methods for control of nematodes and other soil-borne pathogens is soil solarization. In this method solar energy is used to heat up the moist soil to lethal or sublethal levels. The treated soil is adequately prepared and tarped with a tight transparent plastic sheet for six to eight weeks. A team of researchers, headed by the author, and a number of graduate students launched an extensive programme on the testing and development of soil solarization. This method proved highly effective, cheap and safe as compared with chemical treatment. Significant increases in tomato, eggplant, cucumber and musk melon yields were demonstrated. The Jordanian research group also demonstrated the effectiveness of a low-cost method of soil solarization, by simply using a non-perforated black plastic mulch (instead of transparent). At the end of the solarization period, the black plastic is perforated for transplanting.
Farmers in Jordan solve their nematode problems by using nematode-free transplants. In plastic houses and intensive agriculture they fumigate their soils largely with methyl bromide, as a biocide. In other minor cases soils are fumigated with Nemacur or Di-Trapex. The liquid formulation of Vydate is also used and generally applied through drip irrigation systems. More recently, farmers have begun to adopt soil solarization to control soil-borne pathogens both in plastic houses and in the open fields.