اولين گزارش آلودگي گياه توت‏فرنگي به نماتود ساقه و پياز (Ditylenchus dipsaci) در شمال ايران*

FIRST REPORT OF THE STEM AND BULB NEMATODE, Ditylenchus dipsaci, ON STRAWBERRY IN NORTHERN IRAN*

نماتود ساقه و پياز، Ditylenchus dipsaci (Kühn, 1875) Filipjev, 1936، يكي از خسارت‏زاترين نماتودهاي انگل گياهي است كه انتشار جهاني دارد. اين نماتود داراي دامنه وسيعي است و به بيش از 300 گونه گياهي از جمله يونجه، شبدر قرمز، چغندرقند، ذرت، پياز، سير، توت‏فرنگي و بسياري ديگر از گياهان زراعي و باغي، بخصوص گياهان زينتي پيازدار از قبيل نرگس، سنبل و لاله حمله مي‏كند. در ايران اين گونه از گياهان يونجه، سير، پياز و لوبيا گزارش شده است. طي بازديدهاي انجام شده از مزارع توت‏فرنگي مناطقي از شهر‏هاي بهنمير و بابل از استان مازندران نشانه‏هاي بيماري شامل كوتولگي، چروكيدگي و بد‏شكلي برگ‏ها، كاهش طول دمبرگ‏ها و سطح پهنك برگ، كاهش اندازه ميوه و عدم تشكيل ميوه در آلودگي شديد مشاهده گرديد (شكل 1). نماتودها از خاك و اندام‏هاي هوايي توت‏فرنگي استخراج، تثبيت و به گليسرين خالص انتقال داده شدند، سپس با استفاده از ميكروسكپ نوري مطالعه گرديدند. بر اساس ويژگي‏هاي ريخت‏شناختي و ريخت‏سنجي جمعيت استخراج شده از بافت گياه توت‏فرنگي مورد مطالعه D. dipsaci تشخيص داده شد. مشخصات ريخت‏سنجي ماده‏ها و نرهاي بررسي شده به ترتيب بشرح ذيل است: Females (n = 10): L = 1169 ± 121.8 (1011-1411) µm, a = 44.1 ± 2.9 (40.7-51.0), b = 6.3 ± 0.8 (5.0-7.2), c = 14.9 ± 1.6 (13.2-18.6), cʹ = 5.1 ± 0.4 (4.6-5.7), stylet = 11.1 ± 0.7 (10.2-11.8) µm, V = 78.9 ± 2 (74.5-81.3). Males (n = 5): L = 1183 ± 175 (947-1430) µm, a = 50.2 ± 4 (46.2.-50.8), b = 6.4 ± 0.8 (5.8-7.6), c = 14.8 ± 1.2 (13.5-16.2), cʹ = 4.8 ± 0.5 (4.2-5.5), stylet = 11.4 ± 0.2 (11.1-11.6) µm, spicules = 26 ± 1 (24.8-27) µm, gubernaculum = 7.7 ± 0.3 (7.3-8.0). بررسي اوليه نشان داد كه به ترتيب حدود 90 و 40% از 20 و 10 مزرعه نمونه‏برداري شده در شهرهاي‏ بهنمير و بابل داراي نشانه‏هاي بيماري بودند. وقوع بيماري در مزارع مختلف نيز با توجه به قدمت كشت بين 20-70% برآورد گرديد. ميانگين تعداد نماتود در پنح بوته از هر مزرعه 147 عدد در گرم بافت بود. مي باشد.

The stem and bulb nematode, Ditylenchus dipsaci (Kühn, 1875) Filipjev, 1936 is one the most destructive plant-parasitic nematode which is widely distributed in temperate regions of the world. It is a serious pest on a wide range of crops including lucerne, red clover, sugar beet, maize, onion, garlic, strawberry and many other agricultural and horticultural plants, especially flower bulbs such as narcissus, hyacinth and tulip. Ditylenchus dipsaci has been reported from alfalfa, garlic and onion from Iran. Occurrence of D. dipsaci on strawberry, which was first reported in 1913 from Britain, has not already been observed in Iran. During a survey of the strawberry fields in Bahnamir and Babol cities of Mazandaran province, symptoms of disease including dwarf, leaf shrinkage and deformities, reduced petiole length and surface of lamina, reduced fruit size and reduced fruit setting in severe infections were observed. The nematodes in the soil and aerial parts of the infected strawberry plants were extracted by tray method, fixed and transferred to the anhydrous glycerin. After preparing permanent slides, the nematode was studied by light microscopy. On the basis of morphological and the following morphometric characters, the population extracted from infected strawberry, identified as Ditylenchus dipsaci: Females (n = 10): L = 1169 ± 122 (1011-1411) µm, a = 44.1 ± 2.9 (40.7-51.0), b = 6.3 ± 0.8 (5.0-7.2), c = 14.9 ± 1.6 (13.2-18.6), cʹ = 5.1 ± 0.4 (4.6-5.7), stylet = 11.1 ± 0.7 (10.2-11.8) µm, V = 78.9 ± 2 (74.5-81.3). Males (n = 5): L = 1183 ± 175 (947-1430) µm, a = 50.2 ± 4 (46.2.-50.8), b = 6.4 ± 0.8 (5.8-7.6), c = 14.8 ± 1.2 (13.5-16.2), cʹ = 4.8 ± 0.5 (4.2-5.5), stylet = 11.4 ± 0.2 (11.1-11.6) µm, spicules = 26 ± 1 (24.8-27) µm, gubernaculum = 7.7 ± 0.3 (7.3-8.0) µm. Initial investigation indicated that approximately 90% and 40% of 20 and 10 strawberry fields in Bahnamir and Babol cities, respectively, showed the symptoms of disease. The occurrence of disease in different fields was estimated between 20-70%, with respect to the age of cultivation. The average number of nematodes in infected shoots obtained from five plant samples per each field was 147 nematodes per gram of plant tissue.