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Individual study: Root-Knot Nematode Resistant Cowpea Cover Crops in Tomato Production Systems

Published source details

Roberts P.A., Matthews W.C.J. & Ehlers J.D. (2005) Root-Knot Nematode Resistant Cowpea Cover Crops in Tomato Production Systems. Agronomy Journal, 97, 1626-1635


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Crop production: Grow cover crops in arable fields Mediterranean Farmland

A replicated, randomized, controlled study in 1997–2001 in irrigated tomato fields at two sites in the Coachella and San Joaquin Valleys, California, USA, found lower tomato yields in plots with cover crops, compared to dry fallows, but found inconsistent differences in tomato yields between plots with cover crops and wet fallows. Crop yield: Lower tomato yields were found in plots with non-nematode-resistant cover crops, compared to plots with dry fallows, in some comparisons (e.g., in Experiment 1: 40,000 vs 61,000 kg/ha). Inconsistent differences in yields (sometimes higher, sometimes lower) were found between plots with cover crops or wet fallows (e.g., in Experiment 3, in 2 of 9 comparisons: 21,000 vs 59,000–69,000 kg/ha; in 1 of 9 comparisons: 143,000 vs 110,000). Methods: Six experiments compared plots with cover crops (cowpeas Vigna unguiculata: several nematode-resistant cultivars and one susceptible cultivar, sometimes incorporated into the soil, and sometimes not) to plots with fallows (dry or wet) between 1997 and 2001 (4–6 replicate plots/treatment/experiment). Some herbicide, but no fertilizer, was used. In the Coachella Valley, cover crops were sown in late July or early August and suppressed after 70–84 days. The following year, tomatoes were planted in late January or early March and harvested in June. In the Central Valley, cover crops were sown in May and suppressed after 83 days. The following year, tomatoes were planted in April and harvested in August.

 

Pest regulation: Grow cover crops in arable fields Mediterranean Farmland

A replicated, randomized, controlled study in 1997–2001 in irrigated tomato fields at two sites in the Coachella and San Joaquin Valleys, California, USA, found more root-knot nematodes Meloidogyne spp. and tomato roots with more galling (caused by nematodes) in soils with cover crops, compared to dry fallows, but cover crops had inconsistent effects on nematodes and galling, compared to wet fallows. Crop damage: More root galling was found in plots with cover crops, compared to dry fallows (e.g., in Experiment 1: 0.9–2.7 vs 3.2–7.6 root gall index), but inconsistent differences were found between plots with cover crops or wet fallows (sometimes more, sometimes less). Pest numbers: More nematodes were found in soils with cover crops, compared to fallows, in most comparisons (e.g., for dry fallows, in Experiment 2: 4–1,005 vs 1). Implementation options: For cover crops that were not resistant to nematodes, more nematodes were found in soils with cover crops, compared to fallows, in most comparisons (e.g., in Experiment 1: 9,148–9,803 vs 19–599). However, for cover crops that were resistant to nematodes, fewer nematodes were found in soils with cover crops, compared to wet fallows, in some comparisons (e.g., in Experiment 1, in four of 10 comparisons: 3–72 vs 19–599), and more nematodes were found in other comparisons (e.g., in Experiment 4, without incorporation: 26–35 vs 1). Methods: Six experiments compared plots with cover crops (cowpeas Vigna unguiculata: several nematode-resistant cultivars and one susceptible cultivar, sometimes incorporated into the soil, and sometimes not) to plots with fallows (dry or wet) between 1997 and 2001 (4–6 replicate plots/treatment/experiment). Some herbicide, but no fertilizer, was used. In the Coachella Valley, cover crops were sown in late July or early August and suppressed after 70–84 days. The following year, tomatoes were planted in late January or early March and harvested in June. In the Central Valley, cover crops were sown in May and suppressed after 83 days. The following year, tomatoes were planted in April and harvested in August. Nematode juveniles and eggs were counted in soils samples (0–30 cm depth). Root galling was measured at harvest (21 tomato root systems/plot).