For most crops an optimal harvest period can be determined which maximizes harvest quantity and quality. These optimal harvest period are generally determined in the absence of pest pressure. In some instances, when pest pressure is severe enough, harvest quality and quantity can be improved by harvesting earlier than the "optimal" harvest period (Coaker 1987). In these cases losses from pests are accruing more rapidly than gains from additional growing, ripening or drying time. Examples of this tactic include early harvest of potatoes to minimize damage from the potato tuber moth, Puthorimaea operculetta, early harvest of timber to minimize bark beetle damage (Berryman 1986), and early and rapid harvest of almonds in California to reduce harvest infestation levels of the navel orangeworm, Amyelois transitella (Engle & Barnes 1983). One obvious extension of this concept is to systems where a mobile pest may migrate from a harvested crop to a vulnerable field. Research has shown the pea aphid, Acyrthosiphon pisum, and Lygus spp. can migrate from harvested forage alfalfa fields to alfalfa being grown for seed and vegetable fields (Schaber et al. 1990; Stoltz and McNeal 1982). Current pest management generally focuses on a single crop. A truly integrated approach for managing the agroecosystem will entail considering the harvest timing and pattern of all the crops being grown in the local area. The importance of crop sequence and area-wide management concerns is illustrated by the recent problems with Bemisia whiteflies on vegetable crops, cotton, and alfalfa in the desert southwest of the U.S. (Watson & Silvertooth 1992).
Berryman, A.A. 1986. Forest insects: Principles and Practice of Population Management. Plenum Press, New York.
Coaker, T.H. 1987. Cultural methods: The crop. In Integrated Pest Management (Eds. A.J. Burn, T.H. Coaker, and P.C. Jepson), 69-88. Academic Press, London.
Engle, C.E. and M.M. Barnes. 1983. Cultural control of navel orangeworm in almond orchards. Calif. Agric. 37:19.
Watson, T.F., and J.C. Silvertooth. 1992. Seasonal dynamics of sweetpotato whitefly. Proc. 1992 Beltwide Cotton Prod. Res. Conf., pp. 657-664. Memphis: Natl. Cotton Counc.