Greenhouse tests

In screening tests it was observed that this isoparaflBnic oil, at 100% concentration, killed from 85 to 95% of mealy bugs and aphids in the greenhouse. Test plants such as peach, gardenia, squash, com, and bean were uninjured at this concentration. 

There was some indication that the presence of nontoxic oil in the emulsion caused a tendency toward selectivity. For example, a 10% emulsion of either methylnaphthalene or dimethylnaphthalene killed the greenhouse test plants with no selectivity. The addition of 20% nontoxic oil, however, greatly reduced the carrot injury without an apparent reduction in toxicity to the other species. Tests were conducted with water emulsions of highly phytotoxic naphthas which contained 75 to 85% aromatics and had boiling ranges of to 550 F. Excellent selectivity was obtained in some tests, but in other tests the emulsion gave severe injury to carrots. The results with emulsions of high aromatic naphthas were inconclusive. 

Weeds are rapidly becoming resistant to some of the newer herbicides, and it is important to realize the consequences. For example, in Missouri, Bader et al. (1995) conducted a study on corn-soybean rotations in which they used only ALS-inhibitor herbicides, that is, imazethapyr in soybean and primisulfuron-methyl in corn. Within 4 years, a common waterhemp biotype resistant to 5-fold higher rates of ALS inhibitors was flourishing. Greenhouse tests confirmed that ALS-resistant common waterhemp biotypes were present in several plots in the experiment. Within the same state, Bader et al. (1994) reported one case of atrazine-resistant common waterhemp, which developed where a farmer grew continuous com and used only atrazine for more than 10 years. Table 11.1 shows trends in the numbers of herbicide-resistant weeds. 

In the course of developing pesticide candidates, it is often necessary to supply commercial type formulations for advanced greenhouse testing as well as for field plot work. Often requests are... 

Such screening of synthetic compounds typically Involves greenhouse testing of up to a dozen or so Important crop and weed species for both pre-emergence and post-emergence activity. 

Both compounds were field tested at a number of locations. The level of activity observed in the field trials, however, was not sufficient to warrant continued evaluation. Subsequent greenhouse testing suggested that the failure of AC 247,909 to perform in the field may be due to photodecomposition in postemergence tests and to soil metabolism and volatility in preemergence tests. 

Compounds which showed appreciable activity in the primary screens were subjected to secondary and tertiary greenhouse tests. 

Table III. Postemergent Broadleaf Control in Greenhouse Tests...

Table HI. Control of wheat powdery mildew and stem rust in foliar greenhouse tests for phenyl substituted 2-butyl-2-cyano-phenethyltriazoles...

Competitiveness of INA deletion mutants. Greenhouse tests had been conducted to evaluate the competitiveness of the INA strains compared to their naturally occurring parental strains as well as other epiphytic strains. Results indicated that the INA strains are competitive equals with naturally occurring NON-INA and INA+ strains. Application of equally low or high dosages of INA+ and INA bacteria resulted in co-existance without either population predominating. When unequal dosages... 

Eiirther laboratory and greenhouse test methods development is needed to assess the potential adverse effects of genetically altered microbial pesticides. Although some test methods are available atri analysis of field testing proposals can proceed on a case-by-case basis, there is a need for further research in test method development. 

Pyridopyrimidinones, quinazolinones and thienopyrimidinones were all evaluated in the field for powdery mildew control on wheat. Field candidates were applied early in the season as protectants (before substantial presence of the disease). Table 6 shows field efficacy of several substituted pyridopyrimidinones. Although highly active in greenhouse tests, these analogs were less effective than standards, e.g. flusilazole, under field conditions with only moderate levels of mildew control observed at 250-125 g/ha. 

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