Incidence and Etiology of Postharvest Fungal Diseases Associated with Bulb Rot in Garlic (Alllium sativum) in Spain.

Laura Gálvez,Daniel Palmero

doi:10.3390/foods10051063

Abstract

In recent years, different postharvest alterations have been detected in garlic. In many cases, the symptoms are not well defined, or the etiology is unknown, which further complicates the selection of bulbs during postharvest handling. To characterize the different symptoms of bulb rot caused by fungi, garlic bulb samples were collected from six Spanish provinces in two consecutive years. Eight different fungal species were identified. The most prevalent postharvest disease was Fusarium dry rot (56.1%), which was associated with six Fusarium species. Fusarium proliferatum was detected in more than 85% of symptomatic cloves, followed by F. oxysporum and F. solani. Pathogenicity tests did not show a significant correlation between virulence and mycotoxin production (fumonisins, beauvericin, and moniliformin) or the mycelial growth rate. Penicillium allii was detected in 12.2% of the samples; it was greatly influenced by the harvest season and garlic cultivar, and three different morphotypes were identified. Stemphylium vesicarium and Embellisia allii were pathogenic to wounded cloves. Some of the isolated fungal species produce highly toxic mycotoxins, which may have a negative impact on human health. This work is the first to determine the quantitative importance, pathogenicity, and virulence of the causative agents of postharvest garlic rot in Spain.

Highlights

Garlic is a crop of great importance throughout the world and is highly valued for its culinary and medicinal properties
“Wound Damage” was detected in 5.1% of the samples; our results indicate that this symptom is caused by trauma or injuries that occur during harvest or postharvest handling, followed by the growth of pathogenic or weakly pathogenic fungi, such as Fusarium, Penicillium, Embellisia or Stemphylium
Fusarium proliferatum and Penicillium allii were identified as the main causal agents of postharvest fungal diseases in Spanish garlic

Summary

Introduction

Garlic is a crop of great importance throughout the world and is highly valued for its culinary and medicinal properties. Garlic producers have faced new sources of postharvest losses. Pests, and poorly characterized physiological disorders cause significant postharvest garlic losses, but discriminating the symptoms of these agents remains challenging. Postharvest rot is one of the main causes of garlic bulb loss during storage. Its incidence is directly related to the presence of pathogens on harvested bulbs and is greatly influenced by postharvest handling processes, including drying, storage, transportation, and marketing of the bulbs [3,4]. Many pathogens initiate their infection during the development of plants in the field [5]; and the disease progresses during the postharvest period. Some microorganisms may remain dormant and develop during the postharvest period, causing losses of economic importance [6] or acting as inoculum reservoirs in cloves used for sowing

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