Aims To establish protocols for the simultaneous detection and identification of Xanthomonas species causing tomato bacterial spot. Methods and Results We verified the specificity and sensitivity of the previously reported sets of primers designed for strains of the four species of Brazilian tomato bacterial spot xanthomonads, consisting of 30 of Xanthomonas euvesicatoria, 30 of X. vesicatoria, 50 of X. perforans and 50 of X. gardneri. Furthermore, we tested a multiplex PCR protocol for the purpose of concurrent species identification. The possibility of direct detection of the pathogens in diseased leaf samples was also verified. The primers were highly specific, amplifying only target DNA. The sensitivity of the primers in conventional PCR was 50 pg μl⁻¹ for purified DNA and ranged from 5 × 10² to 5 × 10⁴ CFU ml⁻¹ when bacterial suspensions were analysed. The multiplex PCR was suitable for the detection of all four species and showed similar sensitivity to conventional PCR when tested on purified DNA. When using bacterial suspensions, its sensitivity was similar to conventional PCR only when a biological amplification step (Bio‐PCR) was included. Both methods were able to detect the pathogens in symptomatic tomato leaves. Conclusions Brazilian Xanthomonas strains causing tomato bacterial spot can be differentiated and identified at species level by a PCR‐based method and by a multiplex PCR. Significance and Impact of the Study This protocol may be a feasible alternative tool for the identification and detection of these pathogens in plant material and may be used for routine diagnostic purposes in plant pathology laboratories.

ISHS III International Symposium on Tomato Diseases EFFECT OF TEMPERATURE ON PATHOGENICITY COMPONENTS OF TOMATO BACTERIAL SPOT AND COMPETITION BETWEEN XANTHOMONAS PERFORANS AND X. GARDNERI

The study was aimed to evaluate the effect of successive applications of increasing biochar rates along with other mineral fertilizers and poultry manure on onion nutrition and yield. The experiment consisted of 2 (agricultural year) × 11 (treatments) factorial combinations over two cropping years (2017 and 2018). Thus, 11 treatments were tested as follows: C = control; MF = mineral fertilizer; PM = poultry manure; B1+ MF = 1 Mg ha⁻¹ of biochar+MF; B1+ PM = 1 Mg ha⁻¹ of biochar+PM; B2+ MF = 2 Mg ha⁻¹ of biochar+MF; B2+ PM = 2 Mg ha⁻¹ of biochar+PM; B4+ MF = 4 Mg ha⁻¹ of biochar+MF; B4+ PM = 4 Mg ha⁻¹ of biochar+PM; B10+ MF = 10 Mg ha⁻¹ of biochar+MF; B10+ PM = 10 Mg ha⁻¹ of biochar+PM. The highest onion yield (39.9 Mg ha⁻¹) was obtained in 2017 with the biochar rate of 5.9 Mg ha⁻¹ while an increase of 308 kg ha⁻¹ in onion yield was found for each Mg ha⁻¹ of biochar added to soil in 2018. The use of biochar combined with mineral fertilizers increased onion yield; and the use of biochar combined with poultry manure improved soil fertility status.