Field experiments were conducted to determine if aldicarb, disulfoton, or phorate applied in-furrow at 0.84 or 1.12 kg ai ha–1 affected cotton response to clomazone applied PPI or PRE at rates ranging from 0 to 1.12 kg ai ha–1. Disulfoton and phorate greatly reduced clomazone-induced chlorosis, stunting, and death of cotton seedlings. Compared with no insecticide or with dimethoate applied POST, aldicarb did not affect cotton response to clomazone. A clomazone rate by insecticide interaction was not observed for cotton yield. Clomazone reduced cotton yield at one of five locations. Insecticides affected yield at three locations, where highest yields were from cotton treated with aldicarb. In a separate experiment with 0.56, 1.12, and 2.24 kg ha–1 of phorate applied in-furrow and 1.12 kg ha–1 of clomazone applied PPI, phorate at all rates protected cotton from clomazone phytotoxicity.

Cotton tolerance of DPX-PE350 applied POST alone, mixed with acephate, carbaryl, or dimethoate applied at 220, 1100, or 280 g ai ha−1, respectively, or following aldicarb, disulfoton, or phorate applied in the seed furrow at 1.0, kg ai ha−1 was evaluated. DPX-PE350 at 170 g ae ha−1 did not adversely affect seed cotton yield, fiber length, fiber length uniformity, or micronaire but did decrease fiber strength. The insecticides did not alter cotton response to DPX-PE350. Entireleaf morningglory was controlled 92, 95, and 96% with DPX-PE350 applied POST at 56, 110, and 170 g ha−1, respectively. Mixing acephate, carbaryl, or dimethoate with DPX-PE350 did not affect control.

The movement and degradation of agricultural chemicals in soil and groundwater is a complex process, influenced by climatic conditions, site characteristics, chemical properties, and agricultural practices. Because of this complexity, mechanistic models are useful tools in evaluating environmental fate. Although currently available unsaturated zone models often do not provide accurate concentration profiles when compared with field measurements, they can be used to estimate the depth and extent of movement. Another application of modeling is to compare predicted movement under different simulation conditions to determine the significance of the various factors affecting the behavior of agricultural chemicals. When properly designed and interpreted, modeling studies can contribute to the understanding of the environmental fate of agricultural chemicals. When necessary, modeling can also be useful in developing management practices included on the label or in state regulations. Modeling has been a frequently used tool in developing restrictions for minimizing the movement of aldicarb residues into groundwater and preventing residues in drinking water. Examples of model use include optimizing application timing, estimating well setback distances, and identifying vulnerable soils.

Field and greenhouse experiments evaluated interactions of soil-applied insecticides and imazaquin and imazethapyr on growth and development of cotton. Imazaquin and imazethapyr were applied PPI at 0 to 6 and 0 to 16 g ae ha−1, respectively, in the greenhouse (plus a no-insecticide control), and 0 to 72 g ha−1 in the field in combination with aldicarb, disulfoton, and phorate (without a no-insecticide control) applied in the seed furrow. Cotton shoot fresh weight in the greenhouse experiment decreased linearly as herbicide rates increased. Greater reductions in shoot fresh weight were noted with imazaquin than with imazethapyr. Compared with no insecticide, the methylcarbamate insecticide aldicarb and the organophosphate insecticides disulfoton and phorate did not affect cotton response to either herbicide. In the field, cotton injury increased while stand, yield, and maturity decreased as herbicide rates increased. Delayed maturity was due to a lower percentage of bolls produced on sympodia from main stem nodes four to nine. Imazaquin caused greater injury, greater reductions in stand, greater delays in maturity, and lower yields than did imazethapyr. Earlier maturity was noted with aldicarb-treated cotton. Compared with aldicarb, disulfoton and phorate did not alter cotton response to imazaquin or imazethapyr.

Disulfoton and phorate applied in the seed furrow greatly reduce clomazone phytotoxicity to cotton in the field, whereas aldicarb does not. An experiment was conducted to determine the effect of aldicarb, disulfoton, and phorate on 14C-clomazone absorption, translocation, and metabolism by cotton grown in a sandy loam soil. Clomazone at 0.87 μg g−1 of soil alone or in combination with aldicarb at 0.6 μg g−1 of soil reduced cotton root and shoot growth 26 to 33%. Root and shoot growth were not reduced by clomazone plus disulfoton or phorate at 0.6 μg g−1 of soil. Protection of cotton against injury by clomazone was not explained by reduced absorption or translocation of clomazone or a metabolite to the shoot. Clomazone metabolism was reduced by disulfoton and phorate, thus indicating a clomazone metabolite may be more toxic to cotton.

Low doses of the acetylcholinesterase-inhibiting carbamate nematicides disrupt chemoreception in plant-parasitic nematodes. Fluorescein isothiocyanate (FITC)/dextran conjugates up to 12 kDa are taken up from the external medium by certain chemosensory neurons in Caenorhabditis elegans. Similar chemoreceptive neurons of the non-feeding infective stage of Heterodera glycines (soybean cyst nematode) fill with FITC and the nuclei of their cell bodies selectively stain with bisbenzimide. The widely used nematicide aldicarb disrupts the chemoreceptive response of H. glycines with 50% inhibition at very low concentrations (ca 1 pM), some 10−6-fold lower than required to affect locomotion. Similarly, the anthelmintic levamisole had this effect at 1 nM. Peptides selected as mimetics of aldicarb and levamisole also disrupt chemoreception in H. glycines and Globodera pallida at 10−3-fold or lower concentration than required to inhibit locomotion. We propose an uptake pathway for aldicarb, levamisole, peptide mimetics and other soluble molecules by retrograde transport along dendrites of chemoreceptive neurons to the cell bodies and synapses where they act. This may prove to be a general mechanism for the low-dose effects of some nematicides and anthelmintics.

The introduction of high yielding sorghum hybrids in the mid-1960s indicated that the new cultivars were highly susceptible to insect pest attack. Use of chemicals for the control of the snootily, Atherigona soccata (Rondani), became necessary to realise a full yield potential.

This paper briefly reviews the earlier work on conventional foliar sprayings and dustings of the available insecticides which generally failed to give an effective control of the shootfly.

Work carried out in the early 1960s showed that the application of phorate, disulfoton, aldicarb and carbofuran granules in the soil at the time of sowing was very effective in controlling the pest. Recently two more insecticides, viz. isofenphos and fensulfothion have been found to be equally effective. However, the cost of applying these insecticides is rather high.

Seed treatment with carbofuran at 5 parts a.i. per 100 parts of seed proved to be highly effective and economical. It is now being widely used by farmers in the major sorghum growing area of the country. It has been found that dosage of carbofuran can be further reduced by using a 6:4 mixture of treated and untreated seed.

Trials have been conducted to determine the residues of effective insecticides in the soil and in plants at different intervals. Investigations have also been carried out to establish the correlation between the residues of different insecticides in plants and their efficacy in controlling the shootfly. A future strategy for the chemical control of the shootfly is outlined.