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The study was conducted in the laboratories of the Center for Biological Control Research and Studies at the Faculty of Agricultural Engineering, Damascus University, during the period from 2020 to 2024. The results of examining the characteristics of farmers in terms of information about purple nutsedge and methods of controlling it, showed the wide spread of the weed in the study areas and the misdiagnosis of it as a grass plant and thus the wrong prescription of a herbicide to control it, and reliance on agricultural shops for control information. It also showed that a large number of them depended on the use of plant residues (26%), especially banana leaves. Several new plant species were found in aquatic environments, including brown sedge, C. fuscus, papyrus, C. alternifolius, and cock's-foot, Dactylis glomerata, While the most severe competitor to nutsedge in the field was the red-root amaranth, Amaranthus retroflexus, as it allowed the least number of sedge plants (105 plants/m2) compared to the control 310 plants/m2. The phylogenetic tree (dendrogram) was separated into two clusters, the first one included the plants of the central and coastal regions, and the second one included the plants of the southern region of Syria. A large number of visiting insects have been recorded on the plant as well as some its natural enemies, such as Bactra verutana, B. minima minima, and B. bactrana, which was recorded for the first time. The newly hatched larvae crawled on the leaf blade in all directions, and it was noted that one larva started to bore in the leaf blade towards the base of the stem, while the other larvae raise the end of their body, which leads to their transfer with the wind to the neighboring plants. The larva continues feeding until it reaches the top of the basal bulb, and the dead heart phenomenon begins after about (5-10) days from the hatching of the eggs. The larval stage was completed within 19.66 ± 1.19 days. The larva bore the top of the basal bulb, thus damaging the apical bud of the bulb and making a suitable hole for pupation. Five instars were recorded for the larva. The pupa stage lasted from 5-8 (6.48 ± 0.95) days. The life cycle from egg to adult was completed in 29-37 (33.2 ± 1.96) days. The overwintering stage, the fully developed larvae, is in the remains of the plant stems. The results showed that the growth rate of the larval instars is proportional to Diyar's rule, and the increase in size from one instar to another is constant and equal to 1.1996. Egg laying was restricted to sedge plants, C. esculentus (20 eggs), C. fuscus (5 eggs) and C. alternifolius (2 eggs) and to bermuda crass (3 eggs) in the absence of nutsedge plants, but the larvae only completed their lives on sedges, indicating the high specialization of the moth and the possibility of its rearing and release in nutsedge control programs. The reverse migration of sap in nutsedge plants begin after 16-19 days of plant regrowth, and here begins the control with systemic herbicides. Treatment with banana and sweet potato powders gave significant effects on chlorophyll, and the pesticides: Paraquat, Halosulfuron, Rimsulfuron, Glyphosate, 2,4-D, Linuron and Metribuzin gave significant reduction in chlorophyll. The performance of these herbicides improved when urea was added. The synergism of herbicides and plant residues led to a significant reduction in the number of tubers formed on the plant in pots and in the field, and these treatments inhibited the regrowth of new tubers. In the field experiment, the best results were with halosulfuron with plants powder and urea, which gave 3.67 tubers, indicating the high effectiveness of halosulfuron in the growth of purple nutsedge compared to the control (17 tubers). Sweet potato and banana leaf powder proved to be effective in reducing the number of tubers, giving 7.67 and 7.3 tubers respectively, due to the presence of phenolic compounds in them. The number of tubers regrowth after 30 days of incubation decreased to only one tuber out of 3.67 tubers, by 27.78% in the treatment of halosulfuron and plant powders and urea. This may due to entering the tubers into a secondary or physiological dormancy as a result of the biological pressure applied to the plants in the previous growth stages.
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Keywords: Purple sedge, Cyperus rotundus L., sedge stem borer, Bactra, Brooks-Dyar law, herbicides, tubers, Syria, extracts.
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