RESULTS AND DISCUSSION
There was considerable difficulty in judging when to begin harvesting tobacco each year. The objective was to begin one week prior to optimum value. If we had accurately judged that date, all the lines should have peaked at time 2 (optimum value) and then declined (Fig. 1). However, values peaked at time 2 and time 3, and in three environments it peaked as late as time 5. The rainfall during one of the seasons where value peaked at time 5 (RM 94) was below normal in July and August (9.6 cm vs. a normal of 15.5 cm for July and 10.9 cm vs. a normal of 14.4 cm for August). In fact, for those environments when rainfall was below normal for July and August (RM 93, RM 95, and
Dollar value per hectare
b Numerical grade index based on assigned grades.
c Leaf yield per hectare in kg.
d Five weekly harvests beginning one week before optimu
R95) the regression of value on time becomes essentially zero (not significantly different). In addition, RM95 and Reidsville in 1995 (R95) had excessive rainfall in June (33 and 41 cm respectively), which would have stunted normal root growth and may have compounded the problem of below normal rainfall in July and August.