| Summary: | The thermal requirements of <i>Meloidogyne incognita</i> on <i>Phaseolus vulgaris</i> in a set of constant soil temperatures were determined and the phenology model was validated at fluctuating soil temperatures. The base temperature (<i>Tb</i>) and the thermal constant (<i>S</i>) from nematode inoculation to females starting to lay eggs were 11.3 °C and 323 accumulated degree days (DD), respectively; <i>Tb</i> = 10.5 °C and <i>S</i> = 147 DD from egg production to emergence of juveniles; and <i>Tb</i> = 11.1 °C and <i>S</i> = 476 DD for life cycle completion. At fluctuating soil temperatures in pots with the minimum lower than <i>Tb</i> and the maximum higher than <i>To</i> (optimal temperature), the DD calculation was carried out by the average daily temperature–<i>Tb</i> (ADTb) and the single sine method over <i>Tb</i> (SSTb) with horizontal, intermediate, and vertical cutoffs. The most accurate were the ADTb and the SSTb with horizontal and intermediate cutoffs (93–106% of the predicted value) but the vertical underestimated the accumulated DD (75–82% of the predicted value). When fluctuating soil temperatures were between <i>Tb</i> and <i>To</i> in a plastic greenhouse, only the ADTb method was used. Life cycle completion was observed around 465 DD (accuracy between 0.95 and 0.99) at four different transplanting dates.
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