Development of Sustainable Cropping Systems for Canola on Limited-Resource Farms in Alabama

Development of Sustainable Cropping Systems for Canola on Limited-Resource Farms in Alabama

Summary

During 1998-99, we developed production practices for canola. Since canola is a new crop in the United States, very little information exists on various insects affecting production of domestic canola. Therefore, with very active help of our two entomologists, (Drs. Rufina and Ken Ward) we carried out a cursory survey of arthropods associated with canola planted at Alabama A&M University during the 2001-growing season. Initial entomological observations made on local variety trial plots showed several key insect pests adversely impacting canola. The identification of both herbivorous and beneficial insects, as well as obtaining basic information on the bionomics of major pest species, is crucial to formulating future control tactics.

Objectives/Performance Targets

1. 1.) To establish cultural and agronomic production practices of canola;
   2.) Development of sustainable cropping systems for canola in sequences with other crops;
   3.) Comparison of conventional and no-till planting systems in canola production in Alabama;
   4.) Develop information about the economics and profitability of canola;

Accomplishments/Milestones

Cabbage seedpod weevil (CSW) and other insects. Terminals (flower heads) of single plants selected at random were vigorously shaken to dislodge insects into a 10- gallon grocery bag. Five plants per plot were collected weekly from flowering stage to harvest. Bag samples were stored in a walk-in freezer until insect identification and counting. Number of exit holes and weevil counts were determined.
Clover stem borer (CSB). Six whole plants per test cultivar were examined for clover stem borer’s presence and damage. Prior to harvesting, two plants from each entry were cut just above the soil surface from each replication and were used to determine: whole plant weight, seed weight per plant and other physical damage.

Table 1. Insect species collected on canola
Insects Percent
Cabbage seedpod weevil 50.0
False chinch bug 31.3
Flea beetle 8.2
Thrips 4.9
Flies 0.9
Aphids 0.4
Diamondback moth 0.6
Others* 0.8

Data (Tables 1 & 2) showed that despite considerable insects infestations and damage, seed yield of some cultivars was not severely affected, particularly in varieties Acropolis and GA96038A. This information suggests a high economic threshold for cabbage seedpod weevil. However, it must also be noted that feeding damage by other feeding insects and disease infections cause cumulative adverse effects on canola performance and are manifested in low seed yield at harvest. This study was done to compare relative performances of various cultivars. We did not quantify the effects of these factors singly on yield of canola. Several species of insects were collected from canola (Table 1). Based on total number of insects collected, cabbage seedpod weevil was most abundant. Table 2 shows the percentage of Clover stem borer in the canola cultivars sampled.

Table 2. Stem borer %/cultivars
Cultivars Percent
Wichita 50
Plainsman 34
Ceres 34
GA 96200E 34
Bridger 17
Acropolis 17
Explorer 17
Ericka 17
GA 96038A 17
Winfield 0
Jetton 0
Casino 0

Climatic conditions in northern Alabama allow for the cabbage seedpod weevil to become active as early as February when the temperatures begin to rise to 10°C and higher. Cultivars with spring-type characteristics will bolt early and become hosts to weevils coming out of hibernation. If the weevils become active in February, there would be about four months of warm weather from then until harvest time. Depending on the temperature, a full generation of the cabbage seedpod weevil may span over two months in the northern US. Therefore, it is possible that at least a second generation of the cabbage seedpod weevil may occur in north Alabama where adult weevils were observed throughout the flowering season and until canola harvest. This speculation will be observed and verified during the 2001-02-growing season.
Clover stem borer, Languria mozardi (identification verified by G. Baker, Mississippi State University) was detected only during canola harvest. This is the first report of this species on canola in the U.S. CSB was discovered when whole plant samples were being examined for overall insect damage. Hollow stalks were observed in many plants. Further observation revealed the presence of adults and other immature stages of CSB in the excavated stem. Further examination of stubbles in the field showed extensive pith damage in canola stalks. Several immature and adults stages of this insects was also observed in the stubbles; however, counting of the insect to determine the level of infestation was not made. This along with economics and profitability informations will be developed during the 2001-02 cropping season.

Impacts and Contributions/Outcomes

Valuable information is being obtained to provide growers who are interested in adapting canola as an alternate or companion crop to winter wheat but as an oil seed crop for the Tennessee Valley. The pests problems and finding of the new pest as reported here will greatly help to control pests in production practices of Canola.

Collaborators: