Deir Ezzor Research Center, General Commission for Scientific Agric. Research (GCSAR)
Faculty of Agriculture, Al-Furat University,
The Gossypium hirsutum species is considered an important strategic crop in Syria, particularly in north-eastern region. It contributes largely to providing the necessary foreign currency and supporting national income. It is to be mentioned here that yield reached to 4395 kg/ha in 2004.
However, cotton is susceptible to many diseases, primarily verticillium wilt caused by a special kind of fungi called Vertivicillium dahliae, which infect more than 300 woody and herbaceous species, especially olive and solanaceae. Moreover, it is a world wide spread disease, including Syria of course, precisely Deir Ezzor. Due to the fact that the already conducted studies and collected data on this disease in Deir Ezzor failed to focus the light on infection rates and severity, we conducted the research in question. In addition, different salicylic acid and di-potassium hydrogen phosphate concentrations to induce a systemic acquired resistance in cotton plants against V. dahliae can be used. Furthermore, we draw a comparison to determine the best method of treatment with induction materials whether it is the leaf-spraying or root-irrigation method on both local cotton varieties Deir Ezzor22 and Rassafa.
A field survey for cotton verticillium wilt disease in 90 fields in 30 villages on 2 banks of Euphrates River during September and October in 2007 and 2008 was done. The wilt disease was found in all surveyed fields. The highest average rate of infection I. E., 7.00% and 7.67% was found during the 2 years respectively in Al-Tibni village. The highest percentage of wilt severity was recorded as 14.00% during 2007 in Al-Tibni village. It was 14.33% during 2008 in Al-Busayrah village. While, the lowest average rate of infection was detected in Sbikhan and Al-Sawah villages 2.33% and 1.67% during 2007 and in Sbikhan and Al-Sawah villages viz., 3.67% during 2008.
The results show that all the morphological characteristics of cotton vercillium wilt isolations pathogen in the entire fields of governorate were identical to those of V.dahliae. The local isolations cultured on Czapek’s media gave Microsclerotia of 5 g weight per liter after a 15day-incubation at 27±2 C temperature, where CFU concentration mounted up to 4—108 per ml of the fungal suspension.
Salicylic acid 1 m molar concentration had not any fungi stasis on the lab cultures growth of the local isolation compared with the 3 & 9 m molar concentrations. The same thing applies to di-potassium hydrogen phosphate, where the 10 m molar concentration did not have any effect on the inhibition of previous isolations growth in comparison with 30 and 90 m molar concentrations.
Studying the effect of treating the infected Deir Ezzor22 and Rassafa by using local isolations taken from V. dahilae under field artificial infection conditions with a fungal suspension at concentration 4—104 CFU/ ml and with a liter for each 750 g of seeds 24 hrs prior to planting using 0.5 &1 m molar concentration of salicylic acid. The control was treated by ethanol solution to make salicylic acid a soluble and di-potassium hydrogen phosphate with 5&10 m molar concentrations. The control was also treated with water to make di-potassium hydrogen phosphate a soluble using leaf-spraying method at a rate of 10 ml/ plant and root-irrigation method at a rate of 25 ml/ plant once after a month from planting.
ments on infection severity and production characteristics: plant length, boll number per plant, boll weight, lint percentage, technological characteristics: fiber length, uniformity, fiber strength, solidarity, fiber elongation and fiber fineness were studied.
The statistical analysis of the previous readings showed that the characteristics of fiber elongation and fineness remained unaffected during all the final experiment factors. Varieties had not any effect on the following readings: infection severity, plant elongation, plant boll number, boll weight, fiber length and solidarity. Deir Ezzor22 variety was better than Rassafa variety in terms of uniformity and fiber strength.
Induction materials had no effect on the following characteristics: lint percentage, fiber length and strength. On the other hand, salicylic acid transcended in its second concentration the rest of concentration in connection with the upcoming characteristics: infections severity percentage, plant length, this very concentration besides di-potassium hydrogen phosphate outmatched other concentrations in regard to: boll number and solidarity, whereas di-potassium hydrogen phosphate had no effect on: boll weight and uniformity. Two treatment methods using induction materials had no effect on: lint percentage, strength and solidarity. Concerning the rest of treatments, root-irrigation method outmatched leaf- spraying one.