Hazem Sawalha

Arab American University, Faculty of Arts and Sciences, Faculty Member

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Papers by Hazem Sawalha

Chemical Antibacterial Agents Used to Disinfect Cultivation Tools against the Crown Gall Disease of Stone Fruits

Several chemicals were tested and evaluated as antibacterial agents against the Palestinian isola... more Several chemicals were tested and evaluated as antibacterial agents against the Palestinian isolate of Agrobacterium tumefaciens, the causal agent of the crown gall disease. Based on the disk diffusion method on nutrient agar, formaldehyde appeared to be the strongest followed by sulfuric acid, hydrochloric acid, sodium hydroxide, Hypex and Dettol. On the other hand, those chemicals revealed 90-100% inhibition against the bacterial cell contaminating common pins. The other chemicals showed either an intermediate or weak bacterial inhibition of the bacterium on agar nutrient media.

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Scope of Using Treated Olive Mill Wastewater in Tomato Production

International Journal of Agriculture and Forestry, 2014

An experiment was carried out to evaluate the feasibility of using treated olive mill wastewater ... more An experiment was carried out to evaluate the feasibility of using treated olive mill wastewater (OMW) in irrigating tomato crops. The OMW was filtrated using a home-made filter of a matrix that mimics nature. OMW filtration improved physical and chemical properties of the filtrate as it became clear with neutral pH. The results showed that the 10% dilution of the filtrate gave best results compared with those irrigated with tap water. The 20% dilution gave the second best outcome followed by the 50% which gave an intermediate plant growth and production. Irrigation with untreated OMW killed the plants in a couple of days. Treated OMW was found to be useful in irrigating tomato crops at economic level.

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Detection of Three honeybee Viruses in Palestine using RT- PCR

Honeybee viruses cause a serious problem that beekeepers suffer persistently from, in Palestine. ... more Honeybee viruses cause a serious problem that beekeepers suffer persistently from, in Palestine. The presence of honeybee viruses is responsible, with other factors for the recurrent apiary collapse. In the current research, adult and immature bee samples collected from Jenin (1214) , Tulkarm (1016) and Nablus (1032) districts were tested for three honeybee viruses using RT- PCR and specific primers. Deformed Wing Virus (DWV) , Acute Bee Paralysis Virus (ABPV) , and Sac Brood Virus (SBV) were detected in the collected samples with different infection levels. The DWV was the predominant virus infecting honeybees in the studied Palestinian territories. Infection frequencies with this virus were 34 - 86% and 13 - 59% for adult bee workers and broods respectively. ABPV was the second most virus attacking bee colonies in the studied regions, followed by SBV. The maximum infections of adult bee workers with ABPV was 22% whereas 18% infection was recorded for SBV. The mixed infection with ...

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Incidence and Genetic Variability of Erysiphe Cichoracearum, the Causal Agent of Powdery Mildew on Squash and Cucumber in Tubas and Jenin

An-Najah University Journal for Research - A (Natural Sciences)

An experiment was carried out in 2008 to study the incidence of Erysiphe cichoracearum, the causa... more An experiment was carried out in 2008 to study the incidence of Erysiphe cichoracearum, the causal agent of powdery mildew on squash and cucumber in different growing seasons of the Tobas and Jenin districts. The incidence was studied in both open fields and plastic houses. Also, the research studied the genetic variability between the fungal isolates using RAPD. The maximum fungal incidence was recorded on squash, compared with cucumber in all growing seasons. The maximum disease incidence of 70% was recorded on squash during both spring and summer growing seasons in Tobas district. Autumn was considered the second most serious growing season of both crops as the fungal incidence ranged from 4 to 53% and 3 to 42% on squash and cucumber, respectively. In late winter growing season, the fungal incidence was much lower on both crops planted in Tobas district compared with the other growing seasons (4 to 20% on squash and 2 to 18% on cucumber) . In addition, studying the genetic variab...

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Incidence of Viral Diseases on Pepper in Palestine: A Case Study on Potato Virus Y in the Northern Regions of the West Bank Using RT-PCR

Jordan Journal of Agricultural Sciences, Jan 31, 2012

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Occurrence of Tomato Yellow Leaf Curl Virus on Volunteer Tomato, Jimsonweed, and Tobacco in North West Bank: Distribution of Virus Natural Reservoirs in Summer Season

An-Najah University Journal for Research - A (Natural Sciences)

Volunteer tomato (Lycopersicon esculentum), jimsonweed (Datura stramonium) and tobacco (Nicotiana... more Volunteer tomato (Lycopersicon esculentum), jimsonweed (Datura stramonium) and tobacco (Nicotiana tabacum) plants were found to be natural reservoirs for Tomato Yellow Leaf Curl Virus (TYLCV) in the northern West Bank regions using the Polymerase Chain Reaction (PCR). The virus can be maintained in these plants during the summer period in the studied regions. Volunteer tomato plants proved to be the most significant reservoirs for the virus because they are so abundant in all of the studied regions, and they demonstrated a high rate of infection, ranging from 52-95%. The maximum infection of volunteer tomato plants was recorded in the Jericho district and Al-Far'a region to be 95% and 93%, respectively. Under field conditions, TYLCV was found to infect tobacco in one of two ways; either as crops planted near the tomato fields or as volunteer plants scattered in tomato growing sites in the Jenin districts. The maximum infection rate of volunteer tobacco plants and tobacco crops w...

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Open Access Epidemiology of Tomato Yellow Leaf Curl Virus in the Northern Regions

Abstract: A survey was carried out in 2011 to study the epidemiology of tomato yellow leaf curl v... more Abstract: A survey was carried out in 2011 to study the epidemiology of tomato yellow leaf curl virus (TYLCV) in tomato growing sites of the Tobas and the Jenin districts. The survey studied the population of the virus-inoculative whiteflies and the possible virus reservoirs throughout the year. The maximum TYLCV-inoculative whitefly population was recorded in Tobas, compared with the Jenin district in the different growing seasons of tomato. In the Tobas district, the inoculative whiteflies started to appear in March and reached the maximum value of 7 % in July and August. In the Jenin district, the maximum inoculative whitefly population of 6 % was recorded in August. Such whiteflies started to appear in May, which is two months after their appearance in the Tobas district. Furthermore, populations of inoculative whiteflies occurred when farmers started their tomato growing seasons. The appearance of inoculative whiteflies coincided with availability of the virus natural reservoir...

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Quantitative Effects of Single and Multiple Infections with Four Viruses on Tomato Production

Annual Research & Review in Biology, 2014

Studying the quantitative effect of tomato viruses including tomato yellow leaf curl (TYLCV), cuc... more Studying the quantitative effect of tomato viruses including tomato yellow leaf curl (TYLCV), cucumber mosaic (CMV), tomato mosaic (TMV) and potato virus Y (PVY) revealed that tomato productivity and fruit weight were severely affected by the number of viruses infected the plant at the same time. Simultaneous occurrence of the four viruses on tomato plants caused drastic reduction in the number of fruit and weight approaching 96% and 93% respectively. Also, mixed infection of tomato with three viruses reduced the number of fruit and weight by72 -92% and 52-84% respectively. Plant infection with TYLCV alonereduced the fruit number by 77 % and 46% for fruitweight. Single infection by either CMV or TMV caused a reduction in the number of fruit and weight by 63% and 25% or 52% and 12% respectively.

Epidemiology of Tomato Yellow Leaf Curl Virus in the Northern Regions of the West Bank, Palestine

The Open Agriculture Journal, 2013

A survey was carried out in 2011 to study the epidemiology of tomato yellow leaf curl virus (TYLC... more A survey was carried out in 2011 to study the epidemiology of tomato yellow leaf curl virus (TYLCV) in tomato growing sites of the Tobas and the Jenin districts. The survey studied the population of the virus-inoculative whiteflies and the possible virus reservoirs throughout the year. The maximum TYLCV-inoculative whitefly population was recorded in Tobas, compared with the Jenin district in the different growing seasons of tomato. In the Tobas district, the inoculative whiteflies started to appear in March and reached the maximum value of 7% in July and August. In the Jenin district, the maximum inoculative whitefly population of 6% was recorded in August. Such whiteflies started to appear in May, which is two months after their appearance in the Tobas district. Furthermore, populations of inoculative whiteflies occurred when farmers started their tomato growing seasons. The appearance of inoculative whiteflies coincided with availability of the virus natural reservoirs which harbor the virus and support the vector during the crop-free period. Infected cheese weed mallows (up to 12%) and tobacco plants (up to 7%) were the virus sources for whiteflies throughout the year in the Tobas and the Jenin districts respectively. Infected volunteer tomatoes (up to 93%) play a secondary role in the virus epidemiology as they disappear during winter (crop-free period) in both districts.

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