International journal of Horticulture, Agriculture and Food science(IJHAF) Vol-3, Issue-2, Mar-Apr, 2019 https://dx.doi.org/10.22161/ijhaf.3.2.9 ISSN: 2456-8635 www.aipublications.com Page | - 102 - Flowering, Yield and Fruit Quality of Balady Mango Seedling trees as influenced by Parlatoria oleae (Colvee) Infestation Rate Amira S.A. Abd El-Rahman 1 , Moustafa M.S. Bakry 2 and Islam R.M. El- Zoghby 3 1 Horti. Dept., Fac. of Agri. Benha Univ., Egypt. 2 Scale Insects and Mealybugs Research Dept., Plant Protection Research Institute, A.R.C, Dokii, Giza, Egypt. 3 Plant Prot. Dept., Fac. of Agric. and Natural Resources, Aswan Univ., Aswan, Egypt. 2 md.md_sabry@yahoo.com 3 ielzoghby77@agr.aswu.edu.eg Abstract — The present study was conducted to investigate some flowering, yield and fruit quality (fruit physical and chemical properties) measurements of twelve years old Balady mango seedling trees grown in clay- loamy soil under surface irrigation system of private orchard located at Esna district, Luxor Governorate as affected by Parlatoria oleae infestation rate during two successive experimental seasons through duration from early September 2016 till mid August 2018 years. Data obtained during both (2016/2017) and (2017/2018) seasons revealed that dates of first, full bloom and harvesting took place earlier in the uninfested trees (control) as compared to the analogous measurements of either slightly or severely infested ones. Moreover, two yield parameters i.e., number and weight (kg.) of mature fruits harvested per each individual tree were obviously decreased by both P. oleae infestation rates as compared to those of the uninfested trees (control). As for the impact on both fruit physical and chemical characteristics, the uninfested trees exhibited an obvious improve in (average fruit dimensions, volume and weight) and (total soluble solids, total soluble solids / acidity ratio, total sugars, reducing sugars and sucrose contents) associated with lower total acidity %. On the other side, the heavily P. oleae infested trees showed significantly the highest reduction in all studied yield and fruit qualities measurements, except with total acidity %, whereas the trend took the other way around as compared to the free and slightly infested trees. Besides, P. oleae was more active through autumn months particularly during October and November of 1 st and 2 nd seasons, respectively. However, the reverse was true during winter months whereas the least values of P. oleae total population density were detected in both seasons, regardless of infestation rate. Concerning, the relationship between the differences in reduction % in a given desirable parameter from one hand and different infestation rate from the other estimated values of the simple correlation and regression coefficient pointed out the highly significant positive relationship between the increase of one insect per leaf and the increase in reduction of all tested yield and fruit qualitites measurements, except total acidity percentage. Keywords— Parlatoria oleae, mango, yield, fruit physical and chemical properties. I. INTRODUCTION In Egypt, mango (Mangifera indica L.) occupies the third place in acreage after citrus and grapes. Mango fruits are desirable and popular fruits for the Egyptian consumers due to its good flavour, delicious taste, nutritive value and other fruit attractive features (El-Said, 2006). Among several pests of mango trees, Parlatoria oleae is considered one of the most main destructive ones (Bakr et al ., 2009). This pest injures the shoots, twigs, branches, leaves and fruits by sucking the plant sap with the mouth parts, causing thereafter deformations, defoliation, dryness of young shoots twigs, dieback, poor blossoming and death of twig by the action of the toxic saliva and subsequently affecting the commercial value of fruits. Infestation causes conspicuous pink blemishes around the feeding sites of the scales (El-Amir, 2002). A characteristic symptom of infestation by this pest is the appearance and accumulation of its scales on attacked mango parts (Hassan et al ., 2009). Mango trees exhibit variable reactions to the insect infestation depending on plant physical properties or