Cultural Methods and Environmental Conditions Affecting Gray Mold and Its Management in Lisianthus

Abstract

Gray mold, caused by Botrytis cinerea, severely affects the base of the stems of lisianthus (Eustoma grandiflorum) plants as well as the cut stems left after flowers are harvested. This study examined infection of lisianthus plants by B. cinerea under laboratory and commercial greenhouse production conditions typical for Israel and evaluated cultural methods for manipulating disease development in commercial greenhouses. Although the lower nodes of lisianthus stems are typically infected, in this study, the inherent susceptibility of these nodes was less than that of nodes midway up the stem. Greater light intensity (4,860 lux) was associated with significantly more severe stem wounds than lower light intensities of 140 to 1,020 lux. Lower light intensity (140 lux) was associated with significantly more severe leaf infection. The development of gray mold along leaves toward the stem was slower at 26 degrees C than at 18 to 20 degrees C and was fastest at relative humidity (RH) levels close to saturation (>99%). B. cinerea infection developed in all stem wounds exposed to 65 to 99% RH and at temperatures of 12 to 29 degrees C. Infection severity in stem wounds (measured as lesion length) on whole plants was significantly less at 26 degrees C than at 18 or 22 degrees C, and was significantly higher at 99% RH compared with 70 to 85 and 85 to 95% RH. Severity of gray mold was the greatest at 15 to 22 degrees C and 85 to 99% RH. Under commercial greenhouse conditions, supplemental calcium (Ca(NO3)2) applied in fertigation or as a spray led to moderate yet significant reduction in disease severity. In addition, polyethylene soil cover and the use of buried drip irrigation instead of surface drip irrigation suppressed gray mold significantly on cut stems following harvest. Covering the soil with polyethylene also suppressed gray mold significantly as compared with the common practice of growing lisianthus in bare soil.

Elucidating the effect of tomato leaf surface microstructure on Botrytis cinerea using synthetic systems

“…The fungus attacks agronomically important plants, such as grape vine, strawberries, tomato, cucumber and cut roses ( Droby and Lichter, 2007 ; Elad et al., 2016 ). Leaf infection by B. cinerea is an important site for gray mold initiation in tomato plants ( Shtienberg et al., 1998 ) and in other crops ( Elad, 1990 ; Shpialter et al., 2009 ). Hence, leaf surface, where the initial interaction between the fungus and the plant occurs, was the center of the study presented here.…”

Effects of Agronomic Practices on the Severity of Sweet Basil Downy Mildew (Peronospora belbahrii)

“…Similarly, Papas [ 21 ] concluded that B. cinerea in out-of-season tomato ( Solanum lycopersicum ) plants grown in unheated glasshouses in Greece can be limited by adequate indoor air circulation. Similarly, in-bed air circulation has been shown to reduce B. cinerea gray mold in lisianthus ( Eustoma grandiflorum ) [ 22 ].…”

“…A plastic cover with a white upper surface reduced the incidence of B. cinerea infection in strawberry ( Fragaria × ananassa ), compared to bare soil [ 25 ]. Similarly, in lisianthus, the use of a polyethylene barrier between the lower leaves and soil that prevented the lower leaves from coming into contact with the wet soil reduced the development of B. cinerea along the leaves toward the stem and prevented plant mortality [ 22 ]. The prevention of contact between the canopy and the wet soil is not relevant in the case of SBDM.…”

“…Vieira et al [ 29 ] reported decreased incidence of white mold and increased soybean yields when within-row densities were reduced. Lower plant density has also been shown to reduce stem gray mold in lisianthus [ 22 ]. Reducing the number of blond psyllium ( Plantago ovata ) seeds sown per unit area reduced the incidence of downy mildew ( Peronospora alta ) in that crop [ 30 ].…”

Effect of a High Tunnel, Organic Cropping System on Lettuce Diseases in Western Washington

“…Even though leaf wetness and relative humidity were greater in the open fields than in the high tunnels, the elevated air temperature inside the high tunnels combined with leaf wetness and high relative humidity, and possibly also within the lettuce head itself, proved conducive for the growth of B. cinerea. Conidia of B. cinerea germinate over a wide range of temperatures when relative humidity reaches 90% (8) but disease can develop when humidity is relatively low (65%) on wounded crop tissues (15). For this reason and others, B. cinerea creates challenges for resistance breeding.…”