Wheat (Triticum aestivum L.) is grown in many arid regions using fallo
w management whereby no crop is grown in alternate cropping seasons. A
lthough fallowing is important in increasing the availability of water
and nitrogen to crops in many environments, experiments in Israel rev
ealed that water carryover from the fallow season for wheat production
was rare. This paper examines the possibility that improved water use
, and improved root and shoot growth, result from soil sanitation of c
ereal cyst nematode (CCN, Heterodera avenae Well.) in the fallow seaso
n. Pot experiments in controlled environments revealed a dramatic, neg
ative effect of various populations of CCN on wheat root growth. The d
ecrease in root growth was associated with decreased shoot growth and
decreased rates of transpiration. Mechanical pruning of roots mimicked
the effects of CCN infestation indicating that root pruning is probab
ly the primary damage of CCN. In the field, dry weight yields of wheat
were maintained even in continuous wheat management when a soil bioci
de was used to control CCN. It is proposed that the success of the fal
low management is based on the fact that CCN cysts hatch in wet soil d
uring rainy periods of the fallow year but fail to produce a new gener
ation of cysts because no host plants are present.