الفهرس 
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Abstract
Studies on the effect of scale insects and their control, on the growth and ornamental value of some ornamental plants.
This work was carried out at the Experimental Station, Faculty of Agricultural Sciences, Moshtohor covering the period from 197? to 1980.
The aim of this investigation was to survey the insect pests infesting ornamental plants grown at the station, the study of population densities of the black scale Chrysomphalus ficus infesting Livistonia chinensis L. grown in lath-house. This study also incluoed the effects of different media x nutritional treatments and insecticidal applications on the growth and
ornamental value of the plants. Results obtained may be summarized as follows : I.Insect survey :
Four mealy bug species belonging to four genera and two species of scale insects of two genera were found infesting nine genera of ornamental plants. These insect species were iden-
tified. II.Population density of Chrysomphalus ficus on Livistonia chinensis :
Following the population density of Chrysomphalus ficus on Livistonia chinensis in lath-house revealed that reproduction
of the insect was continuous throughout the year. The population density decreased by the increase of the ages of plants. Oviposition did -ot vary all the year around. The fluctuations in numbers may be due to differences in hat-chability or mortalities among first instar nymphs.
III. Effect of different pesticides applications on the growth of Livistonia chinensis L. rows in different media and supplied with different levels of nutrition solutions :
1. Number of leaves : Plants grown in a suitable medium and provided with high level of nutrient solution gave the best results. Results were improved when insect infestation was controlled by insecticidal application. Methidathion gave the best results in this concern.
2.Lencth of leaf petiole : The length of leaf petiole increased by the increase of level of nutrition. Fenvalerate activated the elongation of leaf petiole, especially with higher nutritional levels.
3.Leaf area : Leaf area was increased by the increase of nutritional level. Methidathion gave the best results in leaf area increase, fe’lowed by Fenvalerate and Pacol.
4.Leaf fresh weight : Data showed that the pesticides treatments may be effectual on the fresh weight of the plants received its requirements of aeration and nutrient elements.
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IV.Chemical control :
The best control results for Chrysomphalus ficus were ob-tained by the use of Fenvalerate at 0.0 3% a.i. followed by 1% Pacol then Methidathion. The same trend was also observed with Icerya aegyptiaca. The last mentioned insect was significantly more susceptible to Fenvalerate on highly nourished plants, on the contrary susceptibility to Methidathion was less on plants receiving good nutritional levels, while differences in suscep-tibility observed with Pacol were not significant.
Differences in the susceptibility of Chrysomphalus ficus in plants receiving different nutritional levels were not sig-
nificant. V.Effect of treatments on chemical composition :
Nutritional or insecticidal treatments had little effect
on the dry weight of the leaf. Fenvalerate with the concentration used caused a reduction in nitrogen in treatment MCS3. It also caused some increase in phosphorus in the same treatment in the first year only. No differences were found in K20 content, with the exception of some reduction caused by Fenvalerate in the
first year.
Results indicated that Methidathion caused a constant increase in Fe, Zia and Mn, while Fenvalerate caused some var-iations in their ratios in the first year.
Control plants of the high nutrient levels contained the least content of chlorophyll and carotine indicating the cause of yellowish colour of those plants resulting from heavy infestation.