Selected interspecific hybrids between Lycopersicon esculentum and 11 wild species accessions were evaluated for level and type of resistance to Trialeurodes vaporariorum. The interspecific hybrids were clonally propagated and evaluated for antibiosis to non-sexed adult whiteflies, larvae development to the 3rd or 4th instar and reproduction of a second generation of adults. The test unit was a fully mature and expanded leaf containing only 4 leaflets and an 11 cm stem section sitting in a bottle of weak nutrient solution. One detached leaf-stem section from each entry was randomly placed in one of 12 set positions of a bottle rack. Leaflets were infested by placing 5-10 adult whiteflies on 2 leaflets/entry in small leaf cages for 24 or 48 hrs. Adult mortality was determined after 24 & 48 hrs and instar counts were taken after 14 & 21 days. Second generation reproduction was determeind by placing the 2 leaflets with the highest number of 3rd & 4th instar larvae in a petri-dish and recording adult emergence over a 5-18 day period. Some of the hybrids were more resistant and others were more susceptible that the L. esculentum parent. Resistance was manifested in greater adult antibiosis, reduced number of developed larvae and reduced adult emergence.
W. Alan Erb and Richard K. Lindquist
Claudio C. Pasian, Daniel K. Struve, and Richard Lindquist
The effectiveness of two methods of application of the insecticide imidacloprid in controlling 1) aphids (Brachycaudus helichrysi) on Chrysanthemum plants, Dendranthema ×grandiflora (Ramat) (cv. Nob Hill) and 2) whitefly (Bemisia argentifolii) on poinsettia, Euphorbia pulcherrima (Wild.) (cv. Freedom Red) were compared. Plants were grown in containers with their interior covered by a mixture of flat latex paint and several concentrations of imidacloprid (0, 10, 21, 42, and 88 mg·L–1), or treated with a granular application of the insecticide (1% a.i.) according to label recommendations. All imidacloprid treatments were effective in reducing aphid survival after 8 weeks. The two most effective treatments were: granular (1% a.i.) and 88 mg·L–1 with an average of 0.2 aphid per plant as opposed to 50.4 aphids per plant for the control. The 42-mg·L–1 treatment had an aphid survival rate 1.6 aphids per plant. All imidacloprid treatments were effective in reducing white fly larvae. The 42 and 88 mg·L–1 and the granular (1% a.i.) were equally effective in reducing larvae numbers in lower poinsettia leaves: 0.5, 1.9, 0.9 larvae/2.5 cm leaf disk, respectively, while the control treatment had 62.9. None of the plants given treatments with paint showed any sign of phytotoxicity. These results suggest the possibility of a new application method for systemic chemicals with the potential of reducing or eliminating Worker Protection Standard (WPS) Restricted Entry Intervals (REI) and reducing the release of chemicals to the environment. Chemical name used: 1-[(6-Chloro-3-pyrimidil)]-N-nitro-2-imidazolidinimine.
Robert W. McMahon, Richard K. Lindquist, and Harry A. Hoitink
Student involvement in two research projects at a 2-year agricultural college is described. The students assisted in the process of data collection, tabulation, and the preparation of publications. From participating in these research projects, the students earned academic credit and learned the concepts and processes of scientific methodology. Several student shills, including observation, making judgements, and cooperation among peers, were enhanced through hands-on experience. The research proved to be a very enjoyable learning experience for all of the participants.
Claudio C. Pasian, Daniel K. Struve, and Richard K. Lindquist
The effectiveness of two application methods of the insecticide imidacloprid in controlling 1) melon aphids (Aphis gossypii Glover) on `Nob Hill' chrysanthemum (Dendranthema ×grandiflora Ramat) plants and 2) silverleaf whitefly (Bemisia argentifolii Bellows & Perring) on `Freedom Red' poinsettia (Euphorbia pulcherrima Wild.) were compared. Plants were grown in containers with their interior covered by a mixture of flat latex paint plus several concentrations of imidacloprid (0, 10, 21, 42, and 88 mg·L−1), or treated with a granular application of the insecticide (1% a.i.) according to label recommendations. All imidacloprid treatments effectively reduced aphid survival for at least 8 weeks. The two most effective treatments were the granular application (10 mg a.i.) and the 88-mg·L−1 treatment (0.26 mg a.i). All imidacloprid treatments effectively reduced whitefly nymph survival. The 42- and 88-mg·L−1 treatment and the granular application (1% a.i.) were equally effective in reducing nymph numbers in lower poinsettia leaves. None of the plants given treatments with paint exhibited any phytotoxicity symptoms. These results suggest the possibility of a new application method for systemic chemicals with the potential of reducing the release of chemicals to the environment. Paint and imidacloprid mixes are not described in any product label and cannot be legally used by growers. Chemical name used: 1-[(6-chloro-3-pyrimidil)-N-nitro-2-imidazolidinimine (imidacloprid)