Seasonal Abundance of Aphids on Apple Cultivars and Their Chemical Control

Abstract

The study was conducted out in one of the apple orchards in Baghdad Governorate, Iraq, which is planted with local apple cultivars Kofi, Sharabi and Al-Rahbi, to study the population densities of the green apple aphid (Aphis pomi) and the rosy apple aphid (Dysaphis plantaginea) and to evaluate some chemical pesticides to combat them. The results indicated the appearance of the first green apple aphid A. pomi. It was at the end of October on the Kofi cultivar, and the first appearance of A. pomi on the Sharabi and Al-Rahbi cultivars was in the second week of December, and the highest infection rate was in the first week of May with a population density of 59.10, 50.65 and 16.25 nymphs. /leaf and 5.82, 6.22 and 1.48 adults/leaf and respectively for the three above-mentioned cultivars, while the first appearance of the rosy apple aphid D. plantaginea was in the first week of March on the Kofi cultivar, while the first appearance of D. plantaginea on the Sharabi and Al-Rahbi cultivars It was in the third week of March, and the peak infestation reached in the fourth week of April, with a population density of 81.89 and 60.59 nymphs/leaf and 9.88 and 7.16 8 adults/leaf for both the Kofi and Sharabi cultivars, respectively, and for the Al-Rahbi cultivar, the first appearance was in the week. The third of April, with a rate of 8.24 nymphs/leaf and 0.97 adults/leaf. The results indicated that the Kofi apple trees were the most susceptible to infection compared to the rest of the cultivars, while the Al-Rahbi cultivar was the most resistant to aphid infestation. The results of evaluating the effectiveness of the pesticides Arando, Nestor and Oxymatrine in reducing the population density of the green apple aphid (Aphis pomi) and the rosy apple aphid (Dysaphis plantaginea) also indicated that the pesticide Arando was superior to the rest of the pesticides in combating the insect A. pomi and the relative effectiveness rate reached 72.39% compared to the two pesticides Nestor and Oxymatrine. Oxymatrine, the relative effectiveness of which reached 63.32 and 58.20%, respectively. As for the relative effectiveness of the pesticides on D. plantaginea, it reached an average of 85.77, 88.23, and 94.36% for Oxymatrine, Arando, and Nestor, respectively. Nestor was superior to the rest of the pesticides in Control of D. plantaginea insect.