Soil Spray Research Articles

Efecto del nematicida-insecticida Oxamyl L en aspersión del suelo, inmersión de la semilla y del tratamiento del suelo con Phenamiphos 15 G en ñame (Dioscorea rotundata Poir)

Se establecieron dos ensayos de campo en dos sitios de Puerto Rico (Utuado y Corozal) para evaluar la eficacia de la aspersion al suelo y la inmersion de la semilla del nematicida-insecticida Oxamyil L y el tratamiento al suelo con Phenamiphos 15G en la represión del nematodo, Pratylenchus coffeae (Zimmermann) Filip. Schuur-Stekh y del gusano blanco, Diaprepes abbreviates (L) en ñame (Dioscorea rotundata Poir). Las aspersiones al suelo con Oxamyl L se dirigieron a la base de la planta con un dosificador automático de 20 ml. comúnmente llamado "pistola." En Utuado, dos dosis de Oxamyl L, 0.3 ml. (7,410 µg p. a./ml.) y 0.6 ml. (15,297 µg p. a./ml.) por planta aplicado cada 2 meses, se evaluaron solos y en combinación con la inmersión de semilla en 2,400 p./m. p. a. de Oxamyl L por 15 min. Tambien la inmersión de semilla se evaluó al combinarse con aspersiones foliares de Oxamyl L (4.68 l./ha. cada 15 y 60 días). En Corozal se evaluó la aspersión al suelo de Oxamyl (0.6 y 0.9 ml. p.a./planta cada 2 meses), 0.3 y 0.6 ml. p.a./planta aplicado cada 2 meses combinado con inmersion de la semilla (2,400 p./.m. p. a./15 min.), aspersión foliar a razón de 4.68 l./ha./15 días y tratamientos al suelo con Phenamiphos 15G (0.64, 0.93 y 1.27 g./planta). Al momento de la cosecha los tubérculos se agruparon en categorías de calidad según el grado de pudrición seca causado a la corteza por P. coffeae: alta (0-25%), intermedia (26-50%) y pobre (51-100%); y a base de las perforaciones hechas por la larva de D. abbreviates en las categorías vendibles (tubérculos de alfa y mediana calidad sin barrenos) y barrenado (tubérculos con 1 ó más perforaciones). En ambos sitios se lograron aumentos significativos (P = 0.01) sobre el testigo en el rendimiento de ñames de alta calidad. En Utuado se obtuvieron los rendimientos más altos con 0.3 ml./planta combinado con inmersión de la semilla y con 0.6 ml./planta sin inmersión de la semilla. Las aspersiones de Oxamyl L al suelo (0.3 y 0.6 ml./planta cada 2 meses) no redujeron significativamente el daño causado al tubérculo por la larva de D. abbreviates. Los tratamientos comparables aplicados al follaje tampoco redujeron significativamente el daño causado por la larva. En Corozal se demostró que un aumento en la dosis de 0.6 a 0.9 ml. por planta no aumentó significativamente la calidad ni el rendimiento del ñame. La incidencia del gusano blanco fue bien baja en el ensayo de Corozal.

Influence of method of application of paclobutrazol on soil residues and growth retardation in a ?Starkrimson-Delicious? apple orchard

A 3-year field study was conducted to determine the influence of mode of application of the gibberellin-inhibitor paclobutrazol (PP333), [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4 triazol-1-yl)pentan-3-ol], on PP333 soil residue levels and vegetative growth retardation of 10-year-old ‘Starkrimson Delicious’ (Malus Domestica Borkh.) spur-type apple trees. Treatments were applied in March, 1986 and consisted of foliar or soil sprays (200 ppm, 7 × applications at petal fall (+) 2, 4, 6, 8, 10 and 12 weeks) or a single soil drench (8.2 g A.I./tree) applied to the collar at petal fall. Foliar sprays were applied with and without a plastic ground cover to evaluate the influence of foliar runoff on the degree of soil absorption and its subsequent effect on vegetative growth. PP333 was extracted over a 3 year period (1986–88) from 400 cm2 soil patches located at the drip line of each tree, with the exception of soil drenches which were sampled near the collar. PP333 soil extracts were purified and quantitatively analyzed by HPLC. PP333 soil residue levels following foliar sprays were comparable to the soil spray treatment for each year and decreased at a rate of 50% per year from 1986–1988. Foliar sprays retarded terminal growth in the year of application, whereas the soil spray did not inhibit growth until the following year. PP333 residue levels were highest in the soil drench where growth retardation was evident in 1987 and 1988. The greatest carry-over effect occurred in the soil treatments, especially the soil drench application which resulted in the highest soil residue rates throughout the 3 year period.

LABORATORY SIMULATION FOR EVALUATING THE EFFECT OF DROPLET SIZE ON PESTICIDE PERSISTENCE IN DRY SOILS

Residual quantities of methyl salicylate, sprayed on sand, red loam, and heavy loam soils, were estimated by measuring evaporation rates in a laboratory simulation setup. Methods for homogeneous dissemination of liquid on the surface and for controlling and measuring droplet size and surface concentration were developed. A flow system was built for measuring the time dependence of the vapor concentration in a wind tunnel, at various flow rates. Our experiments have demonstrated that the efficiency of soil spraying is affected by droplet size—the highest residuals were obtained with the biggest droplet diameter. It is clear, however, that the final determination of the optimal droplet size is a function of soil type and agricultural requirements.

Contribution of Soil Spray Deposit from Postemergence Herbicide Applications to Control of Canada Thistle (Cirsium arvense)

Foliage-only, soil-only, and foliage plus soil applications of picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide}, and metsulfuron {2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoic acid} were used to determine the contribution of soil spray deposit to the control of Canada thistle [Cirsium arvense(L.) Scop. ♯ CIRAR] under greenhouse conditions. Herbicide reaching the soil contributed significantly to the suppression of secondary shoot growth, particularly when pots were watered from above. In subirrigated pots, the herbicides showed activity if they were sprayed on moist soil, but not if they were sprayed on dry soil. These results suggest that it is important to shield the soil during postemergence applications of herbicides in greenhouse experiments in order to avoid overestimating foliar activity.

Effects of fungicides and insecticides applied to spring barley sown on different dates in 1976-79

SUMMARY Factorial experiments in 1976–1979 investigated the effects of sowing date, fungicides (ethirimol seed treatments and tridemorph sprays) and insecticides (phorate applied to the soil, and menazon or dimethoate sprays) on powdery mildew, aphids, barley yellow dwarf virus (BYDV) and grain yield of spring barley (cv. Julia in 1976 and 1977; cv. Wing in 1978 and 1979). Late sowing usually increased the severity of powdery mildew, numbers of aphids and incidence of BYDV and generally decreased yield. Responses to pesticides were commonly greater on the late-sown than on the early-sown barley. Response to fungicides are principally attributed to the control of powdery mildew (Erysiphe graminis f. sp. hordei; the target species) but responses to insecticides cannot be attributed to virus control and seem unlikely to be due solely to control of aphids, whose numbers were relatively small. There were some effects of fungicides on aphids and insecticides on mildew, but they were inconsistent and too small to affect crop protection strategies.

Biodegradable Cellophane Bags—A Controlled Release System for Pest and Disease Control and Fertilizer Application in Watermelon

Abstract The use of biodegradable, controlled release, cellophane bags for pest and disease control and fertilizer application in watermelon (Citrullus vulgaris) in Brunei is described. The bags are made of a microperforated nitrocellulose-coated cellulose film which biodegrades completely in three to six months depending on environmental conditions and the thickness of the bag. Two trials (1979 and 1980) with seven replicates were carried out. Fertilizers and chemicals were placed in bags and buried in the middle of the plots, or they were applied in the standard way as soil dressings and sprays. A control plot had no fertilizer or chemical application. Results of the 1979 trial showed no significant differences between treatments even though control plots had a lower number of harvested fruits. In 1980 there was a significant difference between the two treatments and the control. Considerable labour costs are saved using the bags and they have a potential use in many crops.

Effects of trellising, crown bunch handling, and the number of oil emulsion and gibberellic acid sprays on harvest-pruned sultanas

Effects of trellising together with the use of various foliage wire arrangements on the production and quality of harvest-pruned sultanas were studied over 4 years. In one experiment a single wire and four narrow 0.4 m 'T' trellis systems, and in a second experiment four 0.9 m wide 'T' trellis and one 0.4 m narrow 'T' trellis system, were tested. Other treatments superimposed on all trellises included crown bunch removal in early spring or at harvest pruning, one and two alkaline oil-in-water sprays (oil sprays) and gibberellic acid (GA) or no GA spray. There were no differences between the four narrow trellises. Dried fruit yield of these four trellises was greater than that of the single wire by an average of 27%, because of higher bunch and cane numbers. There were also no differences between the four wide trellises except that two of the complex ones had more canes. The narrow trellis NTI (used in both experiments) yielded 27% less than the wide trellises because of fewer bunches per vine, caused by lower cane numbers and fruitfulness. Trellising had no effect on fruit quality and only marginal effects on rate of fruit drying, most probably due to low vigour of the experimental vines. As the complex trellis systems had no advantage over the simpler two wire 'T' trellises, their use in harvest pruning is not advocated. In both experiments two oil sprays produced slightly better fruit quality with faster drying of fruit. Use of two oil sprays is warranted where fruit has to be dried rapidly to minimise risk due to rain damage. Early crown bunch removal did not reduce yield and the best time for bunch removal was 6 weeks after bud burst. Use of GA in harvest pruning is not recommended as it does not improve fruit quality and in some years leads to slower fruit drying.

Comparative Effects of Three EPTC Antidotes

In growth room studies,N,N-diallyl-2,2-dichloroacetamide (hereafter referred to as R-25788) was the most effective of three antidotes for the reduction of EPTC (S-ethyl dipropylthiocarbamate) injury to corn (Zea maysL. ‘United Hybrid 106’). R-25788 reduced EPTC injury to corn as a seed treatment, as an incorporated soil spray, or in nutrient solution in quartz sand nutrient culture. CDAA (N,N-diallyl-2-chloroacetamide) was also an EPTC antidote for corn when applied to the soil or in nutrient solution but was itself toxic to corn when applied as a seed treatment. The antidote 1,8-naphthalic anhydride (hereafter referred to as naphthalic anhydride) was less effective than R-25788 as a seed treatment and was ineffective when applied to the soil. Naphthalic anhydride was the only one of the three antidotes which also reduced EPTC toxicity to green foxtail [Setaria viridis(L.) Beauv.].