Depth Of Incorporation Research Articles

Trifluralin Persistence as Affected by Depth of Soil Incorporation

Bioassay and chemical analyses of residual α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) from greenhouse and field experiments indicated that the persistence of this herbicide is increased by deep incorporation as compared to shallow incorporation or surface application. Laboratory studies using a charcoal vapor trap indicated that trifluralin volatilization decreased with increasing depth of incorporation. Volatilization appears to be an important mode of trifluralin dissipation from the soil.

Inhibition of Cotton and Soybean Roots from Incorporated Trifluralin and Persistence in Soil

Inhibition of cotton (Gossypium hirsutum L.) and soybean (Glycine max (L.) Merr.) lateral roots by alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) was directly related to depth and method of incorporation. Root inhibition of the crop plants was reduced when trifluralin was incorporated shallowly after planting with either a power tiller or a ground-driven tiller, to a depth no greater than 0.5 in above seed placement. A bioassay of the soil showed that disking trifluralin-treated plots before bedding caused the greatest retention of the material 3 weeks later, and that retention was less when the herbicide was applied and shallowly incorporated after planting. Further studies on the relationship of soil persistence of trifluralin to depth of incorporation 6 months after application, showed no herbicide present in plots not incorporated while only minimal residues were found where incorporation was no deeper than 1 in. Residues in plots incorporated below the 2-in depth were moderate at 0.5 to 1 lb/A rates and high at the 2 lb/A rate and above.

Factors Affecting the Vapor Loss of EPTC from Soils

The disappearance of EPTC (ethyl N,N-di-n-propylthiolcarbamate) from soils was studied by steam distilling the remaining EPTC from the soil samples and analyzing the distillates. The most important factor affecting the loss of EPTC from soil was the amount of moisture in the soil. During the first 15 minutes after spraying on the soil surface, 20% of the applied EPTC disappeared from dry soil, 27% from moist soil and 44% from wet soil. The loss was 23, 49, and 69% after one day and 44, 68, and 90% after six days on dry, moist, and wet soils, respectively. No significant loss of EPTC occurred the first few hours after applying granular EPTC to dry soil or soil containing 4 to 6% moisture, but on soil at 15% moisture the loss from granules was 60% in two hours. There appeared to be a critical moisture level for each soil, above which large losses of EPTC occurred after application to the surface or after shallow incorporation. Depth of incorporation was the second most important factor in EPTC loss from soils. Incorporation to at least 2 to 3 inches was necessary to prevent large losses of EPTC when light rain or sprinkler irrigation followed treatment. EPTC was lost at a faster rate on sunny days than cloudy days. Increasing the temperature from 32 to 60 F, increased the rate of EPTC vaporization from moist soil but had no effect on the loss from dry soil.

EPTC Injury to Corn as Affected by Depth of Incorporation in the Soil

EPTC Injury to Corn as Affected by Depth of Incorporation in the Soil

FACTORS AFFECTING THE SELECTIVITY OF 2,3‐DICHLOROALLYLDIISOPROPYLTHIOLCARBAMATE (DI‐ALLATE) AGAINST AVENA SPP. IN WHEAT AND BARLEY

Summary. A series of pot experiments has been undertaken to assess the selectivity of 2,3‐dichloroallyldiisopropylthiolcarbamate (di‐allate) against Avena spp. in wheat and barley. It is shown that depth of incorporation, depth of sowing, variety and temperature can all influence the degree of selectivity. When di‐allate is incorporated deeply before sowing, there is good selectivity against Avena fatua L. (wild oat) in barley, but the order can be influenced by the depth at germination of both crop and weed, since the susceptibility of both species increases with increasing depth. Wheat does not exhibit the same response to depth of sowing but variety and temperature are important; the variety ‘Svenno’ is particularly susceptible, and both ‘Svenno’and‘Atte’are much more susceptible at 20° C than at 10° C. As A. fatua is slightly more susceptible at 10° C than at 20° C, selectivity is greater at the lower temperature.Shallow incorporation of di‐allate after sowing gives a much more general selectivity in both barley and wheat, but there is still some element of risk in wheat. Whereas for barley a layer of only 0.5 in. of untreated soil above the seed is adequate protection against damage by di‐allate, 1–1.5 in. of untreated soil may be required above the seed of wheat, depending on variety and temperature. The success of shallow incorporations is explained on the basis that the most sensitive region of the plant is the 10–15 mm above the coleoptile node, which includes the stem apex and developing leaf tissue. This region is moved up in the soil rapidly in Avena spp. by elongation of the ‘mesocotyl’, whereas in wheat and barley, the stem apex is only moved up considerably later by elongation of the internode above the coleoptile node.2,3,3‐Trichloroallyldiisopropylthiolcarbamate (tri‐allate) as compared to di‐allate has a greater selectivity in barley when the compounds are incorporated deeply; also it has greater selectivity in both wheat and barley when shallowly incorporated after sowing.Facteurs influençant la sélectivité du diisopropylthiolcarbamate de 2,3‐dichloroallyle (di‐allate) appliqué sur blé et sur orge contre Avena spp.

The Herbicidal Effect of EPTC, CDEC, and CDAA on Echinochloa crusgalli with Various Depths of Soil Incorporation

The Herbicidal Effect of EPTC, CDEC, and CDAA on Echinochloa crusgalli with Various Depths of Soil Incorporation