Growing Conventional and Organic Squash with Black Plastic or Straw Mulch and Transitional Squash with Living Mulch

Sustainable vegetable production systems require alternatives to petroleum-based plastic mulch and intensive tillage. This work evaluated the performance of squash in three systems: organic (O), conventional (C), and reduced tillage with living mulch in transition to organic (TR). Treatments in each trial were replicated three times in a randomized block design. In O and C trials, the main plot treatments were black plastic (PL) and straw (ST) mulch. In TR, they were living mulch mowing heights of 15 (S) or 30 cm (T). Subplots were cultivars: ‘Cash Flow’ (CF), and ‘Costata Romanesca’ (CR). The trials were established in 2007 on sandy loam soil at a University research farm in Wanatah, IN. In May, cover crops of hairy vetch and winter rye (O) or winter wheat (C) were incorporated, and in TR strips 1.8-m wide on 2.4-m centers were tilled into white clover sod. Squash (3227 plants/ha in C and O; 3630 plants/ha in TR) were transplanted June 12-14, and straw mulch applied in the row for ST, S, and T treatments within 3 days after planting. Yield of marketable squash 15 to 28 cm long harvested between July 7 and Aug. 31 did not differ between PL and ST (PL 4.4 vs. ST 3.4 kg/plant in C, and PL 3.3 vs. ST 3.5 kg/plant in O) or between S (2.9 kg/plant) and T (3.0 kg/plant). Marketable yield in kg/plant did not differ between cultivars. CF produced greater numbers of marketable fruit than CR in C  (CF 17.2 vs. CR 11.0 fruit/plant) and TR (CF 12.8 vs. CR 8.9 fruit/plant), and a similar trend occurred in O (CF 14.7 vs. CR 11.2). Soil nitrate-N in the surface 15-cm dropped sharply by mid-July in all mulch treatments except O PL. Leaf nitrogen content for CF in mid-July and mid-Aug. averaged 3.7% in C, 4.7% in O, and 3.9% in TR. Pest problems that were not successfully managed in O and TR plots included squash vine borer and Plectosporium Blight. The O and C systems performed acceptably but the TR system needs substantial improvement before it can be recommended. These results should aid in decision-making as growers look for more sustainable practices.