Effect of Row Spacing in the Period Prior to Weed Interference in Peanut Cultivation Under Azorean Conditions

Peanut cultivation currently plays a minor role in Portuguese agriculture, despite the country’s favorable soil and climatic conditions. In the Azores archipelago, where agriculture is a key economic activity, peanut production has recently sparked interest among rural producers. Weeds pose a major threat to crop development, particularly for short-cycle species like peanuts. This study aimed to de-termine the period prior to weed interference (PPI) in peanut crops under two row spacings (40 cm and 60 cm) on São Miguel Island, Azores. Eight treatments were established to represent increasing periods of weed coexistence: 0–15, 0–30, 0–45, 0–60, 0–75, and 0–90 days after emergence (DAE), from emergence to harvest, and a weed-free control. A randomized block design with four replicates was used for each spacing. The weed community included eight species, with Cyperus spp., Digitaria spp., Amaranthus blitum, and Portulaca oleracea being the most prevalent. Weed interference throughout the entire cycle led to yield losses exceeding 81% and 86% at 40 cm and 60 cm row spacings, respectively. The PPI, defined at a 5% yield reduction threshold, occurred within the first week of weed coexistence, underscoring the crop’s high sensitivity to competition during early vegetative stages.