nematicides

Abamectin and emamectin are members of avermectin family which categorized as very effective but in the same time are toxic naturally. Most of products in this family are utilized as pharmaceuticals in both humans & animals and for crop protection. Despite avermectins are having complex chemical structures, but they are produced via synthesis in large scales for commercial use. Plant parasitic nematodes (PPNs) cause severe damages in all parts of their host plants, in addition to yield losses. The available strategies to control PPN include use of insecticides/nematicides but these have proved detrimental to environment and human health. Therefore, this scenario gave an opportunity for the utilization of avermectins (abamectin and emamectin) to control plant parasitic nematodes because of their chemical and biological properties, as well as relative safety. Avermectins have short half-lives and their residues can be eliminated easily through different food processing methods. Both abamectin and emamectin were very effective nematicides which proved capability of reducing PPNs significantly in various crops.

The nematicidal efficacy of abamectin, boron, chitosan, hydrogen peroxide, Bacillus thuringiensis and oxamyl 24% SL against citrus nematode, Tylenchulus semipenetrans were examined on Valencia orange trees under field condition for two successive seasons (2017 and 2018). The experiment was conducted in a Valencia orange orchard infested with citrus nematode at Nubaria, El-Behera governorate, Egypt. The obtained results showed that all the tested treatments reduced nematode final population ((Pf) and reproduction factor (Rf) compared with that obtained from the untreated trees. The highest percentages of Pf reductions (74.5-83.4 %) and (70%-82%) were recorded with oxamyl, boron, abamectin, chitosan and H2O2 in the 1st and the 2nd tested seasons, respectively. Whereas, B. thuringiensis had the least nematode Pf reduction with 60.7 and 55.8% in the 1st and 2nd seasons, respectively. Additionally, all treatments significantly improved orange yield (30.9-83.2% increase), physical fruit parameters and orange juice properties. The highest orange yield increase (83.2%) was recorded with boron treatment followed by oxamyl (70.3%). Also, boron increased total soluble solids (TSS) by 13.6%, volume of orange juice (36.4%) and vitamin C (19.7%) and decreased juice acidity (A) by (16.7%). It is concluded that abamectin, boron and the other tested compounds have potential as non-chemical control strategy tools in managing the citrus nematode. These bioagents reduced the amount of traditional chemical nematicides and are considered to be environmentally safe.

The demand on non- fumigant nematicides was strongly increased in the last few years, and this interesting in nematicides are due to farmers are needed for safer pesticides and increasing of the regulatory pressure on many of the traditional nematicides. The control of plant parasitic nematodes with synthetic nematicides is the most widespread and preferred method, but not always effective enough. The most of synthetic nematicides especially non-fumigants are high toxic to non-target organisms. Thus, Novel non-fumigant nematicides were appeared as alternatives. The group of trifluoromethyl contains both fluensulfone and fluopyram which are different in mode of action than traditional nematicides as organophosphate and carbamate. Meanwhile, results indicated that fluensulfone and fluopyram are promising nematicides. These new nematicides are very different from traditional nematicides; they are more selective, less toxic and safer to use.

Plant-parasitic nematodes (PPNs) are famous aggressive pests that attack several crops worldwide. A lot of farmers are suffering from nematode diseases which cause critical crop losses. At the same time, the most of available solutions for this problem are depending on synthetic nematicides. These chemical nematicides not only cause environmental and health problems but also may cause resistance in nematodes. Despite the occurrence of resistance in nematodes under field conditions still less clear. Therefore, this note is about the registered nematicides in Egypt which may help those who are interested in nematicides. Also, the chemical group and mode of action of nematicides were mentioned according to the insecticide resistance action committee (IRAC) [1] and fungicide resistance action committee (FRAC).