جستجوی مقالات مرتبط با کلیدواژه « water quality » در نشریات گروه « گیاهپزشکی »

Background and Objectives:

 Water pH is one of the most important factors that affects the inefficiency of insecticides against the common pistachio psyllid, Agonoscena pistaciae Burckardt and Lauterer (Hemiptera: Aphalaridae), as the most important pest in Iran's pistachio orchards.

 Materials and Methods:

 In this study, the effect of insecticides including spirotetramat (Monvento® SC 10%) and imidacloprid (Confidor® SC 35%) and pH reducing agents, such as Rectiphier® and Citral pH®, on the reduction of population density of eggs and nymphs of common pistachio psyllid were investigated under field conditions. The experiment was carried out as randomized complete block design with four replications. The samplings were done one day before and 3, 7, 14, 21 and 28 days after spraying.

 Results:

 The results indicated that adding Rectiphier and Citral pH to the insecticides had no significant effect on increasing the efficacy of spirotetramat and imidacloprid on eggs population of pistachio psyllid, and only on 7 days after spraying, adding of Rectiphier to imidacloprid significantly increased the efficiency of the insecticide, and reduced the amount of oviposition of A. pistaciae (91.58%). The results of the effect of different treatments on nymphs population density of A. pistaciae showed that the effect of insecticides + pH reducing agents was more than application of insecticides alone, but their effect was not significant, and only on 3 and 7 days after spraying, Rectiphier significantly increased the effect of imidacloprid. The reduction of nymphal population densities in imidacloprid + Rectiphier treatment were 90.13% and 93.23%, on those sampling dates, respectively. 

Discussion:

PH reducers (Rectifier and Citral pH) could have the potential to increase the efficacy of spirotetramate and imidacloprid or other insecticides to control A. pistaciae and produce healthy crops, reduce costs, environmental hazards and side-effects on natural enemies and to minimize application of chemical insecticides. However, more research is needed with regard to the effect of different compounds of pH reducer, different concentrations of those compounds and also the effect of these compounds on different water pH. 

In order to study the effect of soil nitrogen content and water hardness on glyphosate efficacy on common lambsquarter (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.) control، an experiment was carried out as a completely randomized design in a factorial arrangement with three replications. Experimental treatments were included soil nitrogen content (18، 50، 90، 200 and 300 mg/kg soil)، glyphosate doses (0، 75، 100، 125، 150، 175 and 200 % glyphosate recommended dose for common lambsquarter (5 lit/ha) and redroot pigweed (3 lit/ha))، calcium carbonate concentration in water (0، 100، 300، 600 and 1200 ppm). Results showed that increasing water hardness decreased glyphosate efficacy in control of two weeds and increased glyphosate ED50 parameter. Minimum (1453. 17 and 906 gr a. i ha-1 for common lambsquart and redroot pigweed، respectively) and maximum (3424. 45 and 1606 gr. a. i ha-1 for common lambsquart and redroot pigweed، respectively) glyphosate ED50 was observed in 0 and 1200 ppm of water hardness respectively. Increasing soil nitrogen content from 18 to 300 (mg/kg soil) increased glyphosate efficacy in two weeds and glyphosate ED50 decreased from 3217. 03 and 1745. 2 to 1612. 58 and 896. 49 (gr. a. i ha-1) for common lambsquart and redroot pigweed، respectively. Based the results of this experiment، increasing water hardness، ghlyphosate efficiency decreased on weeds control and increasing soil nitrogen content can decrease the negative effect of water hardness on ghlyphosate efficacy.