Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2001
Publication Date: N/A
Interpretive Summary: Kenaf and sunn hemp are starting to be grown in the South as industrial fiber crops. Fiber from these crops can be used to make high quality paper, ropes, and many other products. Kenaf and sunn hemp are generally resistant to insects, which increases their usefulness as crops. However, kenaf supports high levels of reproduction by some kinds of root-knot nematodes in the soil. Since kenaf and sunn hemp are increasingly being grown in rotation with cotton, a 6.0 billion dollar crop in the U.S., it is very important to know how kenaf and sunn hemp will change the makeup of the soil-borne nematode pests that attack cotton roots. In this study, effects of growing kenaf and sunn hemp on the reproduction of southern root-knot and the reniform nematode were examined. These are the two most important nematode pests of cotton in the United States. The results showed that if the kind of nematode in a field is known by a farmer, selection of kenaf and sunn hemp can maximize profits and prevent nematode problems from increasing in subsequent cotton crops grown in the same field.
Technical Abstract: Kenaf and sunn hemp are industrial fiber crops that are being grown increasingly in areas where cotton is the major crop. The most problematic nematodes on cotton are the southern root-knot nematode, Chitwood, and the reniform nematode. For nematode management, it is important to know the comparative effects of kenaf, sunn hemp, and cotton on nematode population densities in the soil. The objective of this study was to clarify the host status of kenaf and sunn hemp to M. incognita and R. reniformis by directly comparing reproduction of each nematode on each crop with the same nematode's reproduction on nematode-resistant and nematode-susceptible cotton. Comparisons were made in six experiments under growth chamber, microplot, and field conditions. The results confirmed that sunn hemp is resistant but revealed it is not equally resistant to M. incognita and R. reniformis. Reproduction of R. reniformis on sunn hemp was nearly undetectable while reproduction of M. incognita was greater than on resistant cotton (Auburn 623, Auburn 634) and up to 20% of that on susceptible cotton (Deltapine 16, Deltapine 50, or Deltapine 5409). Kenaf was confirmed to elevate populations of M. incognita to levels that devastate cotton but found to support substantially less reproduction by R. reniformis than cotton does. Two populations of R. reniformis differed substantially in reproduction on kenaf even though the same populations reproduced similarly on cotton. In conclusion, distinguishing M. incognita from R. reniformis will be essential to the management of nematodes in rotations involving kenaf, sunn hemp and cotton.