White Petroleum Research Articles

Toxicity of Sprays and Spray Ingredients on Pear Psylla Nymphs

Experiments were conducted on nymphs of the pear psylla, Psyllia pyripyri, with various combinations of the following ingredients: Bordeaux (2-40-100), nicotine sulfate, free nicotine, Derrisol, M-P Insecticide, white petroleum oils, pine oil, Hardwood neutral oil, and Penetrol. The trials were made in commercial orchards, using a large spray rig. All the ingredients showed toxicity toward psylla nymphs at the various strengths used. The percentage of dead nymphs varied directly with the proportion of white oil, but nicotine (1-3200) showed a certain toxicity which appears to be but slightly increased by larger dosages. The several ingredients when mixed seemed to increase the destructiveness of the resultant mixture by an amount equal to the sum of the specific toxicities of the components. It is indicated that the nicotine content of psylla nymph sprays can be considerably reduced provided other toxic materials are added which do not react unfavorably with the nicotine. The percentage of white oil can be reduced in the spray mixtures if nicotine in pine oil or Hardwood neutral oil be added. Pine oil and Hardwood neutral oil show promise of reducing materially the nicotine content of the regular spray. Penetrol in bordeaux with reduced nicotine dosage was tested the most extensively and appears to be safe to foliage during the spring application if normal temperatures prevail.