Simple correlations between pea yields and October-through-March, April, May, and June precipitation were 0.52, –0.03, 0.22, and 0.44, respectively; the correlation between heat degree (above 25.6°C) day sum during blooming and pod filling with yield was –0.42. Multiple regression coefficients indicated that October-through-March, April, May, and June precipitation contributed 10, –3, 13, and 16 kg/ha per mm, respectively, to the yield. Each degree day above 25.6°C decreased the yield by 13 kg/ha. All coefficients except for April precipitation were highly significant. Approximately 65% of the year-to-year variation in pea yields was accounted for by these weather variables. Overwinter precipitation and excess heat each accounted for 27% of the pea yield variability. This model can be used to project pea yields based on the current moisture situation in this geographic area. Probabilistic description of weather information can be used along with this model to project probable pea yields.
Maturity effects on yield of fresh peas (Pisum sativum L.) were identified by yield-tenderometer measurements. A percent yield-tenderometer reading relationship was shown to be a useful means for yield adjustment to a common maturity—100 tenderometer reading. Analysis of random error in the predicted percent yield, as a function of tenderometer reading, indicates the need to plan harvests within the 90 to 110 tenderometer range. Alternatively, the yield-tenderometer reading relationships show the possible magnitude of errors incurred in comparing green pea yields when no adjustment is made for dissimilar tenderometer ratings.
Pea root rot is a serious economic threat to pea production in the Great Lakes region. The primary causal organism is Aphanomyces euteiches Drechs., which is responsible for an estimated 10% annual crop loss. A fall oat (Avena sativa) rotation before spring pea planting reduces disease severity. To better understand the beneficial effect of oat on A. euteiches, isolated individual pathogen lifecycle stages of zoospores, mycelium, and oospores were treated in culture with oat extract. Resulting mycelial mats were dried and weighed. Treatment with 90%, 70%, 50%, and 30% oat extract resulted in significant spore germination and mycelial growth of A. euteiches. In the presence of nutrient solution, oat extract concentrations of 90%, 70%, 50%, and 30% significantly enhanced spore germination and mycelial growth of the pathogen. These results demonstrate that the use of oat extract results in dosage dependent germination and growth of A. euteiches.