Many nematode species are found in association with dry bean roots. Two species that cause significant yield reductions are the root-knot (Meloidogyne spp.) and lesion (Pratylenchus spp.) nematodes. These species and the chrysanthemum foliar nematode, Aphelenchoides ritzemabosi, recently reported on bean in Wyoming, are discussed below.
Root-knot nematodes are most abundant and cause greater yield loss in beans in well- drained sandy soils. These nematodes are seldom found in soils with more than 40 percent clay or silt. Infective larvae are most active at soil moisture levels of 40 to 60 percent of field capacity. Eggs may be killed in saturated soils with anaerobic conditions.
Root knot nematode feeding symptoms seldom are readily noticeable on aboveground plant parts. Symptoms from severe nematode damage appear as stunted growth, chlorosis, and wilting during periods of high temperature and moisture stress. These symptoms can be similar to those induced by nutrient deficiencies. Root symptoms of nematode infection vary with the kind of nematode.
Root-knot nematodes cause a swelling or gall formation at the point of root infection. Nematode-induced galls are solid, swollen, root tissue and, when numerous, roots may appear malformed, shortened and thickened. The altered root growth restricts uptake of water and minerals, and may result in wilting and defoliation. However, root-knot nematode problems on dry bean are rare in the Central High Plains.
Incorporation of green manure crops such as sudangrass, sesame, rapeseed, white mustard, or perennial ryegrass the season before dry beans are planted can reduce some nematode populations.
Practice a two-year or longer crop rotation to nonhosts such as small grains. Practice weed control in and around fields, since some weed species also serve as hosts for root-knot nematodes and can increase population levels in the soil. Deep plowing, long fallow periods, and flooding reduce root-knot nematode populations, but often are not compatible with standard dry bean production practices in the High Plains. No Great Northern or pinto variety grown in this region is resistant to root-knot nematodes.
Chemical nematicides may be effective, but are expensive and may not be justified unless yield losses are high. Nematicides used on a previous crop in the rotation, i.e., sugar beet or potato, may exhibit some beneficial carryover effects on the following bean crop.
Product List for Root Knot Nematode:
Pesticide |
Product per acre |
Remarks |
Nematicide/Insecticide |
||
|
Mocap EC |
2.0-2.9 fl oz/1000 ft banded 1-1.33 gal broadcast |
Restricted use; preplant incorporate 2 to 4” deep. |
|
Temik |
7.5-15 oz/1000 ft banded 7-14 lb broadcast |
Restricted use; drill 2-3” below or to the side of seed; 90 day PHI |
Fumigant |
||
|
|
|
Restricted use; Preplant application, aerate 7-14 days. |
|
Telone C-17 |
10-17 gal |
Restricted use; Preplant application, aerate 7-14 days. |
|
Vapam |
40-100 gal |
Restricted use; Preplant application, aerate 7 days. |
|
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
||
Categories: Dry Bean, Disease, Root Knot, Nematode
Date: 04/01/2007