Muwaffaq R. Karajeh

Virulence of root-knot nematodes, Meloidogyne spp., on tomato bearing the Mi gene for resistance

Three species of root-knot nematodes, Meloidogyne javanica, M. incognita races 1 and 2, and M. arenaria race 2 occur in Jordan. These species and their races were identified using morphological characters, the North Carolina differential host test, and SCAR-PCR. The virulence of 83 isolates belonging to Meloidogyne species and races was assayed. The virulence assay was based on the isolate reproduction rate on a resistant tomato cultivar Betterboy bearing the Mi gene for resistance, and was compared with that on the susceptible tomato cultivar Rutgers. Three M. javanica isolates were highly virulent on the resistant cv. Betterboy as indicated by their high root gall index (4.73) and high reproduction factor (3.73). The horticultural parameters (shoot and root fresh weights and root dry weight) were negatively correlated with the reproduction factor.

Efficacy of Saccharomyces cerevisiae on controlling the root-knot nematode (Meloidogyne javanica) infection and promoting cucumber growth and yield under laboratory and field conditions

Saccharomyces cerevisiae is a promising plant growth-promoting yeast for different crops. Applicability of S. cerevisiae as a biocontrol agent of the root-knot nematode (Meloidogyne javanica) was investigated on cucumber under growth-room and field conditions. The yeast S. cerevisiae similar to the nematicide, Ethoprophos, when applied as a rhizospheric soil drench treatment led to an obvious reduction of root galling caused by M. javanica and resulted in reducing the nematode reproduction ability on cucumber under growth room and field conditions. The yeast was more effective at 10 than at 5 g/l. Furthermore, the application of S. cerevisiae resulted in improving cucumber plant growth and increasing its fruit yield. High content of total phenolics in cucumber roots of S. cerevisiae-treated plants and hydrogen peroxide-treated plants gives a clue on the ability of the yeast to induced plant resistance in a similar way to exogenous hydrogen peroxide.

Effects of deficit irrigation on tomato and eggplant and their infection with the root-knot nematode under controlled environmental conditions

Deficit irrigation has been widely investigated as a valuable strategy for dry regions where water is the limiting factor in crop cultivation. Soil moisture can be one of the important factors that influence root-knot nematode (RKN) disease development. To determine how different levels of irrigation can affect disease development, irrigation regimes ranging from 20% to full field capacity (FC) were applied to tomato and eggplant plants inoculated with Meloidogyne javanica (M. javanica) under controlled conditions. In addition, in vitro bioassays were done to evaluate the effect of water potential and soil moisture content on M. javanica viability in the soil and reproduction on plant hosts. The relative egg hatching percentage decreased significantly with decreasing water potential from –0.1 to –1 MPa. The use of 80% irrigation level caused minor reductions in growth but significantly reduced nematode infection load. Nematode infection was reduced even further at lower levels of irrigation, however this also led to marked reductions in fresh and dry weights of the tomato and eggplants. Therefore, deficit irrigation could be used at a rate of 80% or 60% of FC to increase water use efficiency and reduce the level of RKN (M. javanica) infection without greatly reducing the growth performance of tomato and eggplant crops.

Greenhouse evaluation of deficit irrigation on the growth of tomato and eggplant and their interactions with Meloidogyne javanica

Deficit irrigation is considered to be an important approach for crop cultivation in dry regions where water resources are scarce. Deficit irrigation can be used also to decrease the level of infections by some moisturedependent plant pests and diseases such as root-knot nematode disease. Therefore, deficit irrigation at levels of 20%, 40%, 60% and 80% of field capacity was evaluated on tomato and eggplant in either the presence or absence of the root-knot nematode Meloidogyne javanica under greenhouse conditions. At irrigation levels of 20%, 40% and 60%, there was a significant decrease in leaf area, leaf water potential and growth parameters of tomato and eggplant compared to 80% and 100% of field capacity. In addition, a significant reduction in root galling and final nematode population occurred with deficit irrigation levels. Therefore, deficit irrigation at 80% of field capacity can be used to enhance water use efficiency and to increase the effectiveness of the current control strategies to control M. javanica without greatly affecting the growth of tomato and eggplant. However, more studies are still needed to confirm these results under different field conditions.

Root-Knot Nematode (Meloidogyne javanica) – Deficit Irrigation Interactions on Eggplant Cropped under Open Field Conditions

Abstract To investigate the influence of deficit irrigation on the root-knot nematode, Meloidogyne javanica, and its interaction with the eggplant crop, field experiments were conducted at two drip-irrigated agricultural areas in Jordan. Effects of limiting irrigation levels to 80, 60, 40 and 20% of the field capacity (FC) were compared with full irrigation (100%) treatment. Growth of eggplant plants was greatly reduced at irrigation levels of 40 and 20% FC at one field location, suggesting that the influence of deficit irrigation is field-dependant. Fruit yield was similar at all irrigation levels, except at 20% level, where a lower yield was noticed compared to 100% irrigation. Root galling of eggplant caused by the nematode was significantly lower at irrigation levels of 20 and 40% than 80 and 100% of FC, but was field-dependant at 60% of FC. The final nematode population was obviously lower at irrigation levels of 20, 40 and 60% than 80 and 100%. Thus, deficit irrigation to levels of 40 or 60% of FC can be utilised for the management of M. javanica infection in eggplant under field conditions.

Effects of nitrogen fertilisers on the Javanese root-knot nematode Meloidogyne javanica and its interaction with cucumber

The influence of different nitrogen salts at five electrical conductivity levels (EC 2, 4, 6 and 8 mmhos/cm) on the Javanese root-knot nematode (RKN) (Meloidogyne javanica) and its interaction with cucumber was evaluated under in vitro, growth chamber and greenhouse conditions. Percentages of egg-hatching and second-stage juvenile viability of M. javanica were greatly reduced when NH4Cl, (NH4)2SO4 and NH4NO3 were used especially at the higher levels of EC and accompanied with reduction in cucumber root galling. The lower root galling (less than 2.5) was accompanied with NH4Cl, (NH4)2SO4 and (NH4)2HPO4, while KNO3 and NH4NO3 resulted in moderate root galling. In contrast to the nitrogen salts, NaCl caused a reduction in both nematode infection and root growth especially at higher EC levels and this could be due to salinity effect. Diammonium phosphate was superior over the tested salts in increasing plant and root fresh and dry weights and cucumber phosphorus content, while KNO3 was superior in increasing in plant content of potassium.

Pre-harvest bagging of grape clusters as a non-chemical physical control measure against certain pests and diseases of grapevines

Organic grapes are increasingly traded internationally. The main principle of organic grape production is the avoidance of synthetic pesticides to protect fruits from pests and diseases. As a physical control measure, cluster bagging with different types of bags was evaluated under field conditions. Cluster bagging, with or without pesticide treatment, using brown paper bags has significantly reduced grape berry moth infestation to 1.8 and 2.3%, black mold to 0.6 and 2%, gray mold to 2.2 and 1.1%, and powdery mildew to 0.0 and 5.4%, respectively, compared to non-bagged control where 95.2% clusters were damaged by the insect larvae, 93% rotten by the secondary infection of black mold, 26.1% by gray mold, 63.1% damaged by powdery mildew, and 15.2% attacked by birds. The application of pesticides did not increase the efficiency of bagging since bagging with brown paper bags without pesticides has provided grape clusters with almost complete physical protection against grape berry moth, black and gray molds, powdery mildew, and attacking birds which make it suitable for organic agriculture. Furthermore, the use of brown paper bags has improved fruit quality and yield of grapes but delayed the time of ripening compared to the use of clear or black plastic bags that have made grape cluster to ripen early. The use of clear plastic bags has resulted in developing abnormal overgrowths and sunburn. Therefore, the use of paper bagging could provide a useful tool to protect grape clusters from pests and diseases and to improve its organic production.

Molds Associated with Olive Fruits Infested with Olive Fruit Fly ( Bactrocera Oleae ) and Their Effects on Oil Quality

Olive is the most widely grown fruit tree in Jordan; it is annually attacked by the olive fruit fly, Bactrocera oleae (Rossi), whose larvae usually cause great economic losses in fruit yield. Alternaria solani, Aspergillus niger, Cladosporium herbarum, Fusarium solani, Penicillium digitatum, P. italicum and Rhizopus stolonifer were found associated with the fly infestation with a sample frequency ranging from 6.7-33.3%. Penicillium digitatum was the most dominant species. All molds were vulnerable for a hot water treatment at 50 and 70oC as indicated by their low spore germination and colonyforming unit except for P. digitatum and P. italicum which were the most heat-tolerant. When the olive oil was inoculated with pure cultures of these molds, the mold fungi were able to colonize olive oil. Rhizopus stolonifer was the greatest colonizer and besides Alternaria solani, both had obviously reduced the oil peroxide value over the control without greatly affecting the oil free fatty acid content.

Evaluation of Okra Landraces and Accessions Response to the Root-Knot Nematode , Meloidogyne Javanica = تقييم استجابة سلالات الباميا المحلية و خطوطها لنيماتودا تعقد الجذور Meloidogyne Javanica

Thirty-seven landraces and accessions of okra were evaluated under controlled growth conditions; seven of them were further evaluated under open field conditions for their response to the root-knot nematode, Meloidogyne javanica in Jordan. Their degree of susceptibility or resistance ranged from highly susceptible to moderately resistant. International landraces; TOT 581 (from Bangladesh), Egypt Green (from Egypt), TOT 7963 (from Guatemala), TOT 2739 (from Malaysia), Palestine landrace, TOT 7957 (from USA), TOT 7346 (from Vietnam) and USA red and some local Jordanian landraces (Jordan 12, Jordan 34, and Jordan 169) were found moderately resistant (root galling index (RGI) is 2 and reproductive factor (RF) ranged from 1-5). Egypt Red, Jordan 3, Jordan 8, Jordan 48, Jordan 52, Jordan 84, TOT 1767 (from India), India Prabhani, India Sade, TOT 7159 (from Malaysia), TOT 7164 (from Myanmar), TOT 7101 and 7102 (from Philippines), TOT 7343 and 7345 (from Vietnam), and TOT 7966 (from Yugoslavia) were moderately susceptible (RGI=3 and RF ranged from 3 to more than 5). Egypt Green, Egypt Red, Jordan 8 and USA lee gave moderately resistant reactions under open field conditions. Therefore, more efforts should be directed toward intensive breeding of okra for high resistance to the root-knot nematode.

Checklist of Host Range of Root-Knot Nematodes ( Meloidogyne Species and Races ) in Jordan = قائمة المدى العوائلي لنيماتودا تعقد الجذور ( Meloidogyne Species and Races ) في الأردن

Root-knot nematodes, RKNs (Meloidogyne species and races) are widely distributed throughout the irrigated agricultural areas in Jordan which differ in their environmental conditions. In this study, host plant range of local populations of RKNs was revised in Jordan and new host samples were collected from some agricultural areas. Thirty one plant species belonging to 19 different plant families were reported as hosts for RKNs in Jordan. Some plant species were recorded for the first time as new natural hosts including: rosemary (Rosmarinus officinalis) to M. incognita race 1, jungle rice (Echinochloa colona), and Mallow (Malva sylvestris) and wild barley (Hordeum spontaneum) to M. javanica. Some of the studied areas e.g. Al-Eina, Karak was recorded as a new site for RKNs. The results of this study may provide useful information for the management of RKNs in Jordan.