Induced resistance to cyst and root-knot nematodes in cereals by DL-β-amino-n-butyric acid

Foliar sprays and soil drenches with DL-beta -amino-n-butyric acid (BABA) reduced the number of Heterodera avenae and H. latipons cysts on wheat and barley. Foliar sprays of wheat with 8000 mg l(-1) BABA reduced the number of H. avenae cysts by 90%, whereas 2000 mg l(-1) BABA was enough to reduce the number of H. latipons cysts by 79%. Multiple spray treatments with 2000 mg l(-1) BABA at 10-day intervals reduced the number of H. avenae cysts on wheat and barley. A soil drench of wheat with 125 mg l(-1) BABA reduced the number of H. latipons cysts by 93% and H. avenae cysts by 43%. Second-stage juveniles of these nematodes penetrated and formed syncytia in wheat roots soil-drenched with BABA. More adult males of H. avenae were produced in BABA (less than or equal to 250 mg 1(-1))-treated wheat roots (similar to 76%) than in untreated roots (27%). Soil drenches with higher concentrations of BABA inhibited development of adult males and females. Several chemical elicitors of induced resistance were tested for their ability to reduce the number of H. avenae cysts on wheat. Only BABA was found to be an effective resistance inducer. The number of egg masses of an unidentified Meloidogyne sp. root-knot nematode, which infects only monocots, was also reduced by 95% by a soil drench of wheat with 500 mg l(-1) BABA. Development of this nematode inside the BABA-treated roots was also inhibited.