Repellent activity of Tanacetum parthenium (L.) and Tanacetum vulgare (L.) essential oils against Leptinotarsa decemlineata (Say)

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is one of the most destructive pest species to have developed resistance to most chemical insecticides. We determined the composition and evaluated the potential of Tanacetum parthenium L. and Tanacetum vulgare L. (Asteraceae family) essential oil (EO) application as an alternative eco-friendly control strategy against L. decemlineata. We assessed the antifeedant activity for L. decemlineata larvae and adults by estimating the damage to potato leaves treated with three concentrations of EOs dissolved in ethanol (0.125, 0.25 and 0.5%). Results showed that T. parthenium EO was more effective against larvae, and T. vulgare was more effective against adults. In an olfactometer assay, the time required to choose an untreated leaf disc did not depend on the Tanacetum species, or life stage examined. However, the concentration of EO exhibited a significant effect on the behaviour of both developmental stages. At higher EO concentrations, both third instar larvae and adults require less time to choose an untreated leaf disc. Additionally, T. parthenium EO provoked more rapid movement away from the treated leaf disc than T. vulgare, especially at the highest concentration. Successful modification of L. decemlineata behaviour by the two Tanacetum oils suggests that they possess the potential for use in potato protection.

Effect of Copper Hydroxide on Slug Feeding

Kocide® 2000 (53.8% copper hydroxide) and Kocide® 4.5 LF (37.5% copper hydroxide) were examined for their effectiveness at reducing slug feeding using rates found on the Kocide® label. The marsh slug, Deroceras laeve (Müller), was given a choice among two untreated lettuce leaf plugs, one untreated leaf plug and one leaf plug treated with Kocide® 2000 at the rate of 4600 ppm Cu(OH)2 (3.0 tbsp/gal), and one untreated leaf plug and one leaf plug treated with Kocide® 2000 at the rate of 9200 ppm Cu(OH)2 (6.0 tbsp/gal). In a follow-up trial, D. laeve were exposed to Kocide® 4.5 LF at rates of 3100 ppm Cu(OH)2 (1.33 pt/A) and 6200 ppm Cu(OH)2 (2.66 pt/A). A second species, the three-banded slug, Lehmannia valentiana (Férussac), was presented with one untreated lettuce leaf plug and three treated leaf plugs using Kocide® 2000 at the rates of 3100, 6300, and 9400 ppm Cu(OH)2 (2.0, 4.0, and 6.0 tbsp/gal). In each study, D. laeve and L. valentiana showed a preference for the untreated lettuce, indicating that Kocide® 2000 and Kocide® 4.5 LF effectively reduce feeding in these common pest species.

EFFECT OF ZINC APPLICATIONS ON CORN AT TWO SITES EXHIBITING LOW PLANT TISSUE ZINC CONCENTRATIONS IN PRINCE EDWARD ISLAND

No yield responses to applied Zn occurred on corn (Zea mays L.) at two Prince Edward Island sites where untreated leaf Zn concentrations were 11 to 14 μg g−1. Both soil- and foliar-applied Zn increased leaf and whole-plant Zn concentrations. Key words: Banded Zn, foliar-applied Zn, corn yield

TRANSLOCATION AND PERSISTENCE OF TOPICALLY APPLIED DIAZINON AND PHORATE IN BEANS

Diazinon (O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate) and phorate (O,O-diethyl S-[(ethylthio)methyl] phosphorodithioate) were each applied to one leaf of each of 48 bean (Phaseolus vulgaris L.) plants to trace translocation and persistence within the growing plant. Both insecticides moved readily from the treated leaf to the opposite leaf and upward into the shoot. Residues appeared in the stem, but downward movement into the roots was limited. With diazinon, only the parent compound was recovered; with phorate, the sulfoxide and sulfone metabolites were the major fractions after the 1st day. By 14 days after treatment, total residues of phorate and its metabolites had diminished to 0.02 ppm or less, except in the treated leaf itself; diazinon levels had decreased to 0.02, 0.04, and 0.08 ppm in the untreated leaf, stem, and shoot, respectively.

''Ripening'' Tobacco with the Ethylene-Releasing Agent 2-Chloroethylphosphonic Acid

Treatment of flue-cured tobacco with the ethylene releasing agent 2-chloroethylphosphonic acid (CEPA) caused mature leaves to lose their green colour and turn yellow. The treated leaves appeared to go through a partial "yellowing'' or "colouring" phase prior to harvest. Treated leaves at harvest contained greater amounts of reducing sugars and lower levels of starch, relative to comparable untreated leaves. At the end of the curing process, comparisons between treated and untreated leaf showed that only small differences existed in total nitrogen, total alkaloids, starch, and reducing sugars. Statistically, protein of leaf treated with CEPA was significantly lower as compared to untreated leaf. For all yellowing times, dollar values per hundred weight of cured leaf from treated plants were higher than from untreated plants, but the average weight per leaf from treated plants was lower. During the curing process, leaf treated with CEPA can probably be subjected to shorter periods of yellowing or colouring than untreated leaf. If further work with "ripening'' chemicals such as CEPA show that they can be used to hasten yellowing or ripen tobacco successfully, as well as to reduce the time required for curing the crop, economic advantages are likely to accrue. It is to be hoped that such chemicals may help reduce the labour and investment required for crop production, and at the same time improve crop quality