Stemphylium Leaf Blight of Garlic (Allium sativum) in Spain: Taxonomy and In Vitro Fungicide Response

Abstract

The most serious aerial disease of garlic is leaf blight caused by Stemphylium spp. Geographical variation in the causal agent of this disease is indicated. Stemphylium vesicarium has been reported in Spain, whereas S. solani is the most prevalent species recorded in China. In this study, Stemphylium isolates were obtained from symptomatic garlic plants sampled from the main Spanish production areas. Sequence data for the ITS1–5.8S–ITS2 region enabled assignation of the isolates to the Pleospora herbarum complex and clearly distinguished the isolates from S. solani. Conidial morphology of the isolates corresponded to that of S. vesicarium and clearly discriminated them from S. alfalfae and S. herbarum on the basis of the size and septation pattern of mature conidia. Conidial morphology as well as conidial length, width and length:width ratio also allowed the Spanish isolates to be distinguished from S. botryosum and S. herbarum. Control of leaf blight of garlic is not well established. Few studies are available regarding the effectiveness of chemical treatments to reduce Stemphylium spp. incidence on garlic. The effectiveness of nine fungicides of different chemical groups to reduce Stemphylium mycelial growth in vitro was tested. Boscalid + pyraclostrobin (group name, succinate dehydrogenase inhibitors + quinone outside inhibitors), iprodione (dicar-boximide), and prochloraz (demethylation inhibitors) were highly effective at reducing mycelial growth in S. vesicarium with EC50 values less than 5 ppm. In general, the effectiveness of the fungicide was enhanced with increasing dosage.

A study of Eggplant Leaf Spot Disease in Greenhouses at Basrah Province

“…Also, the results indicated that all fungicides inhibited the growth of both fungi C. oxysporum and C. lunata (100%), while they inhibited the growth of A. alternata in a percent of 81.1% with significant differences between them. This study agreed with Chatidimopoulos & Pappas (2016) and Gálvez et al (2016) who found that the fungicide Ortiva inhibited the growth of pear leaves spot disease caused by Septoria pyricola and garlic leaves spot disease caused by Stemphylium sp. This result was also in agreement with Al-Zubaidi (2005) who found that the fungicide Topas was one of the best fungicides using for inhibition the growth of date palm leaves spot pathogens.…”

“…This result was in agreement with Willis & Mavuso (2007) who mentioned that the fungicide Ortiva was very effective against avocado leaf spot caused by Pseudocercospora purpurea. Also, it was found that Ortiva can be used against garlic spot disease (Gálvez et al, 2016). Rohini et al (2015) found that the fungicide Carbendazim 50% gave the highest percentage of eggplant leaf spot disease protection.…”

DNA methylation and integrity in aged seeds and regenerated plants

“…Fungal contamination can be a problem when working with seeds and seedlings, especially after high humidity storage. To discard samples that show fungal contamination on DNA extracts, we tested for PCR amplification products of fungus-specific DNA regions using the internal transcribed spacer (ITS) region of the ribosomal DNA repeat cluster, as well as markers for the specific detection of three fungi genera commonly found in seeds: Fusarium , Penicillium , and Aspergillus (Gálvez et al, 2016; Gil-Serna et al, 2016). The universal primer pair ITS1-ITS4 was tested (5′-TCCGTAGGTGAACCTGCGG-3′ for ITS1 and 5′TCCTCCGCTTATTGATATGC-3′) for ITS4 (White et al, 1990) and other markers specific included an elongation factor specific for Fusarium (5′-ATGGGTAAGGAGGACAAGAC-3′/5′-GGAAGTACCAGTGATCATGTT-3′) (O'Donnell et al ., 1998) and betatubuline-specific for Penicillium and Aspergillus (5′-GGTAACCAAATCGGTGCTGCTTTC-3′/5′-ACCCTCAGTGTAGTGACCCTTGGC-3′ respectively) (Glass and Donaldson, 1995).…”

Effectiveness of Different Classes of Fungicides on Botrytis cinerea Causing Gray Mold on Fruit and Vegetables

“…The quantity and quality of the extracted DNA were assessed using a BioSpectrometer (Eppendorf, Hamburg, Germany). The ITS region was amplified with the primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) in a 20-μl reaction mixture using Pfu polymerase (Gálvez et al, 2016) (Elpis, Daejeon, Korea). DNA sequencing was performed by Macrogen Inc. (Daejeon, Korea).…”