Calcium oxide, potassium phosphite and a Trichoderma enriched compost water suspension protect Capsicum annuum against Phytophthora capsici by priming the immune system.

BACKGROUND: Proper management of Phytophthora capsici in pepper cultivation is extremely important, since Phytophthora blight is the main disease of this crop worldwide. In the past, the main strategy adopted had been the use of fungicides, causing, in some cases, the development of P. capsici resistant strains. In this work three different treatments selected from previous studies (potassium phosphite, calcium oxide and a water suspension from Trichoderma sp. TW2 enriched compost) were tested to prove their ability to activate the systemic acquired resistance (SAR) in pepper against P. capsici; acibenzolar-s-methyl was used as positive control. Two independent growth chamber pot experiments were performed, spatially dividing the site of treatments application (as radical drench) and the site of inoculation (as agar plug on the third leaf). RESULTS: Leaf lesions were measured, showing a significant reduction on all treated plants compared to the untreated control. To further confirm this hypothesis, the expression levels of three SAR key genes (CaPBR1, CaPO1 and CaDEF1) were evaluated though RT-Real Time PCR at the three end-point times: T0, T6 and T24. A significant increase of target genes expression at least in one end-point time in each treated plant was observed. Eventually, statistical overaccumulation of salicylic acid was observed in the upper leaves at the same end-point times, through HPLC-MS/MS analysis. CONCLUSION: This work confirmed the hypothesis that the three treatments tested have the ability to prime the plant immune system, leading pepper to an alert status able to confer a better defence against P. capsici. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Susceptibility of gerbera and chrysanthemum varieties (Gerbera jamesoni and Chrysanthemum morifolium) to Fusarium oxysporum f.sp. chrysanthemi.

In 2002, gerbera plants (cv Kaliki) were observed exhibiting symptoms of a wilt in a soilless cultivation at Albenga area (Northern Italy). A similar wilt was also observed in the Sanremo area (Northern Italy) on cv Red Bull, Anedin and Gud finger grown in soil. The same observations were carried out in 2004 in SW Spain where gerbera plants showing wilt symptoms were observed in soilless crops. In all cases, the planting material originated from the Netherlands. Recently on the base of experimental trials F. oxysporum f. sp. chrysanthemi was recognized as the causal agent of wilts of gerbera both in Italy and in Spain. The aim of this experimental work was the evaluation of the resistance/susceptibility of available cultivars of chrysanthemum and gerbera to the Fusarium wilt. The pathogenicity of two isolates of Fusarium chrysanthemi obtained from infected gerbera (Gerbera jamesonii) and chrysanthemum (Chrysanthemum morifolium) plants was tested on several varieties both of gerbera and chrysanthemum in 2004-2006. In 2004 and 2005 respectively 54 and 30 cultivars of chrysanthemum and 57 and 55 of gerbera were tested, while in 2006 only 53 cultivars of gerbera were tested. The results showed that respectively in 2004 and 2005 67 and 33 % of chrysanthemum cultivars were highly resistant to F. chrysanthemi obtained from chrysanthemum while 57 and 53 % were highly resistant to strain isolated from gerbera. In 2004, 2005 and 2006 47, 65 and 75 % of gerbera cultivars were highly resistant to F. chrysanthemi obtained from chrysanthemum and 48, 56 and 72 % were highly resistant to the strain isolated from gerbera.