The Effect of Solute Potential and Water Stress on Black Scorch Caused by Chalara paradoxa and Chalara radicicola on Date Palms

Abstract

Date palm trees (Phoenix dactylifera) were found to be infected with Chalara radicicola and Chalara (Thielaviopsis) paradoxa in 1992. Compared with healthy palms, most of the diseased palms appeared to be drought stressed and poorly maintained in landscape settings and nurseries. Water potential studies conducted in growth chambers with 5- to 6-leaf seedling plants subjected to water stress at -2.3 MPa had relatively larger necrotic lesions that developed into cankers, death of buds, and eventually plant death. Tissue necrosis was directly related to water potential. Histological studies showed many necrotic islands of parenchyma tissue in drought-stressed infected plants. Only a few inoculated plants in the growth chamber study died without developing extensive cankers, apparently due to the invasion of the crown or terminal bud by the pathogens. In vitro studies with potato dextrose agar amended with glycerol, NaCl, and KCl to decrease the osmotic matrix-based water potential of the media (-4.25 MPa) resulted in a decrease in the radial growth, biomass, and the sporulation of C. radicicola and T. paradoxa. Solute potential of -0.35 to -1.97 MPa, however, favored the growth of both fungi. Sodium chloride had the greatest effect on the growth characteristics of both fungal species. These studies indicate that in parts of Kuwait where drought and salinity prevail, opportunistic pathogens such as C. radicicola and T. paradoxa could become aggressive and cause serious damage to date palms.

First report of Chalaropsis punctulata on date palm in Egypt, comparison with other Ceratocystis anamorphs and evaluation of its biological control

“…paradoxa produces aleurioconidia in chains, whereas Ch. punctulata has aleurioconidia borne singly (Abdullah et al 2009;Al-Ani 1958;Paulin-Mahady et al 2002;Suleman et al 2001). Measurements of endoconidia and aleurioconidia revealed that our dimensions are similar to the ranges reported by Suleman et al (2001) and Polizzi et al (2007).…”

Incidence of the Two Date Palm Pathogens, Thielaviopsis Paradoxa and T. Punctulata in Soil From Date Palm Plantations in Elx, South-East Spain

“…These species either alone or in combination are involved in black scorch of leaves, heart bud rot, bending head, root rot, terminal bud rot and inflorescence rot disease of date palms (Abbas and Abdula 2003;Abbas et al 1997;Djerbi 1983;El-Morsy 1999;Suleman et al 2001).…”

“…Unlike the root pathogens, T. basicola and T. thielvioides were frequently isolated from field soil by using carrot discs and umbelliferous root tissues (McIiveen and Edginton 1972;Yarwood 1946), T. paradoxa and T. punctulata have been mostly isolated from aerial parts of palms (Abbas and Abdula 2003;Abbas et al 1997;Djerbi 1983;El-Morsy 1999;Suleman et al 2001Suleman et al , 2002. However, the present study reports the frequent isolation of these two pathogens from soil using dilution plate, direct soil plating or by soil treatment either with acetic acid or with phenol (Table 1).…”

The interaction of plant biotic and abiotic stresses: from genes to the field

“…In both sorghum and the common bean, drought-treated plants had a higher susceptibility to the charcoal rot fungus Macrophomina phaseolina (Diourte et al, 1995;Mayek-Perez et al, 2002). Similarly, drought stress increased the spread of fungal and bacterial leaf scorch symptoms on date palms and the Parthenocissus quinquefolia vine (McElrone et al, 2001;Suleman et al, 2001). Exposure of Arabidopsis to drought stress allowed greater infection levels of an avirulent isolate of P. syringae (Mohr and Cahill, 2003).…”