Influence of black nightshade (Solanum nigrum) and hairy nightshade (Solanum physalifolium) phenology on processed pea contamination

Abstract

Fruit of black (Solanum nigrum) nightshade and hairy nightshade (S. physalifolium var. nitidibaccatum) contaminate processed peas. The phenology of flower bud appearance (FBA) and flowering in both species was quantified using thermal time (base temperature (Tb), 6 °C) across five sowing dates, to inform management strategies. There was no photoperiod requirement for flowering in either species, hairy nightshade developed earlier (FBA, 352 °Cd; flowering, 509 °Cd) than black nightshade (FBA, 434 °Cd; flowering, 633 °Cd) but had a slower fruit growth rate than black nightshade. Hairy nightshade fruits reached the pea contamination threshold (3 mm diameter) prior to those of black nightshade. A comparison of processed pea cultivar maturity and sowing date showed that cultivars with a short thermal time to maturity (< 730 °Cd, Tb 4.5°C) would have a reduced risk of contamination by black nightshade but not by hairy nightshade.