INFLUENCE OF SUMMER COVER CROPS ON GROWTH AND YIELD OF A FOLLOWING TOMATO CROP IN SOUTH FLORIDA

Authors: WANG, Q - UNIV. OF FLORIDA; KLASSEN, WALDEMAR - UNIV. OF FLORIDA; BRYAN, H - UNIV. OF FLORIDA; ABDUL BAKI, AREF; LI, Y - UNIV. OF FLORIDA

Submitted to: Journal of Florida State Horticulture Society
Publication Type: Proceedings
Publication Acceptance Date: 9/22/2002
Publication Date: 5/22/2002
Citation: Wang, Q., Klassen, W., Bryan, H.H., Abdul Baki, A.A., Li, Y. 2002. Influence of summer cover crops on growth and yield of a following tomato crop in south florida. Proc. Florida State Hort. Soc. 116: 140-143.

Interpretive Summary:

Technical Abstract: A field experiment was conducted to evaluate the effects on populations of nematodes in tomato plots on which three legume cover crops (sunn hemp, Crotalaria juncea; velvetbean, Mucuna deeringiana; and cowpea, Vigna unguiculata) had been grown, and some had been kept as a weed-free fallow and treated with methyl bromide-chloropicrin (MC-33). During tomato flowering, weed-free fallow followed by MC-33 strongly suppressed populations of plant-parasitic nematodes (Helicotylenchus spp., Pratylenchus spp., Rotylenchulus reniformis, and Quinisulcius spp.), but some non-plant parasitic nematodes (dorylaimids and rhabditids) survived at low levels. Sunn hemp strongly suppressed the above-mentioned populations of the plant-parasitic nematode taxa present, except Helicotylenchus spp., which were present in substantial numbers. Also, sunn hemp allowed substantial numbers of Tylenchus, dorylaimids, Mononchus, and rhabditids to survive. Velvetbean strongly suppressed Aphelenchus, Pratylenchus and Mononchus, but allowed survival of significant populations of Helicotylenchus spp., and small or moderate populations of R. reniformis, Quinisulcius, Tylenchus dorylaimids, and rhabditids. Cowpea exerted a strong general suppressive effect on all nematode taxa except the rhabditids. Nevertheless, cowpea allowed low level survival of nematodes in significant plant-parasitic taxa, i.e., Helicotylenchus, Pratylenchus, Rotylenchulus reniformis and Quinisulcius. Cowpea strongly suppressed Aphelenchus spp., but allowed some survival of Tylenchus, dorylaimids, Mononchus, and rhabditids. By the time that the tomato fruit had been harvested, the total numbers of nematodes had increased in all of the treatments. Between tomato flowering and fruit harvest, the increase in the total population of nematodes was 852% in the cowpea treatment, 237% in the weed-free fallow plus MC-33 treatment, 60% in the sunn hemp treatment and 10% in the velvetbean treatment. In the cowpea treatment Pratylenchus and Rotylenchulus reniformis populations did not increase, and most of the increase occurred in the non-plant parasitic taxa. In the weed-free fallow plus MC-33 treatment, Aphelenchus and dorylaimid populations increased the most, followed by increases in the plant-parasitic Helicotylenchus and Pratylenchus. Also in this treatment, one tomato plant heavily infected with the root-knot nematode, Meloidogyne, was found. In the sunn hemp treatment, the population density of Helicotylenchus had doubled and only small changes had occurred in the numbers of other taxa. In the velvetbean treatment the modest build up of Aphelenchus was the most notable change. Unfortunately the plots were not infested with any of the nematodes known to severely reduce tomato yields in Florida, i.e., root-knot (Meloidogyne incognita), sting (Belonolaimus spp.) and stubby root (Trichodorus spp.) nematodes.