Aflatoxin contamination of important food and feed crops occurs frequently in warm tropical and subtropical regions. The contamination is caused mainly by Aspergillus flavus and A. parasiticus. Aflatoxin contamination negatively affects health and trade sectors and causes economic losses to agricultural industries. Many pre- and post-harvest technologies can limit aflatoxin contamination but may not always reduce aflatoxin concentrations below tolerance thresholds. However, the use of atoxigenic (non-toxin producing) isolates of A. flavus to competitively displace aflatoxin producers is a practical strategy that effectively limits aflatoxin contamination in crops from field to plate. Biocontrol products formulated with atoxigenic isolates as active ingredients have been registered for use in the US, several African nations, and one such product is in final stages of registration in Italy. Many other nations are seeking to develop biocontrol products to protect their crops. In this review article we present an overview of the biocontrol technology, explain the basis to select atoxigenic isolates as active ingredients, describe how formulations are developed and tested, and describe how a biocontrol product is used commercially. Future perspectives on formulations of aflatoxin biocontrol products, along with other important topics related to the aflatoxin biocontrol technology are also discussed.

In recent decades, the cultivated area and production of nuts and olives have increased, driven by an increasing consumer interest in healthier food. Diseases of almond, pistachio, olive, and walnut crops caused by species belonging to the Botryosphaeriaceae family have caused concern worldwide. Although considerable progress has been made in elucidating the etiology of these diseases, scientific knowledge of other aspects of these diseases is more limited. In this article, we present an overview of the most important diseases caused by Botryosphaeriaceae fungi affecting almond, pistachio, olive, and walnut crops by focusing on ecology and epidemiology, primarily in California and Spain.

In California, aflatoxin contamination of almond, fig, and pistachio has become a serious problem in recent years due to long periods of drought and probably other climatic changes. The atoxigenic biocontrol product Aspergillus flavus AF36 has been registered for use to limit aflatoxin contamination of pistachio since 2012 and for use in almond and fig since 2017. New biocontrol technologies employ multiple atoxigenic genotypes because those provide greater benefits than using a single genotype. Almond, fig, and pistachio industries would benefit from a multi-strain biocontrol technology for use in these three crops. Several A. flavus vegetative compatibility groups (VCGs) associated with almond, fig, and pistachio composed exclusively of atoxigenic isolates, including the VCG to which AF36 belongs to, YV36, were previously characterized in California. Here, we report additional VCGs associated with either two or all three crops. Representative isolates of 12 atoxigenic VCGs significantly (P < 0.001) reduced (>80%) aflatoxin accumulation in almond and pistachio when challenged with highly toxigenic isolates of A. flavus and A. parasiticus under laboratory conditions. Isolates of the evaluated VCGs, including AF36, constitute valuable endemic, well-adapted, and efficient germplasm to design a multi-crop, multi-strain biocontrol strategy for use in tree crops in California. Availability of such a strategy would favor long-term atoxigenic A. flavus communities across the affected areas of California, and this would result in securing domestic and export markets for the nut crop and fig farmer industries and, most importantly, health benefits to consumers.

Olive (Olea europaea subsp. europaea var. europaea) is one of the first domesticated and cultivated trees that is widely distributed in the Mediterranean regions. The Anthracnose, caused by the two complex fungal species Colletotrichum acutatum and C. gloeosporioides, is the most important disease adversely affecting the olive oil quality. Even so, the effect of Anthracnose on oil quality is largely unknown and many questions remain unanswered. This offers a unique opportunity to study how Colletotrichum species, cultivars, infection type (latent or visible) and severity, and other factors that may affect different parameters of oil quality, such us acidity, peroxide value, K232, K270, phenolic compounds, or alkyl esters. This review focuses on the current knowledge of the biology, epidemiology, and management of Anthracnose and its effect on olive oil quality.

Olive anthracnose caused by Colletotrichum species causes dramatic losses of fruit yield and oil quality worldwide. A total of 185 Colletotrichum isolates obtained from olives and other hosts showing anthracnose symptoms in Spain and other olive-growing countries over the world were characterized. Colony and conidial morphology, benomyl-sensitive, and casein-hydrolysis activity were recorded. Multilocus alignments of ITS, TUB2, ACT, CHS-1, HIS3, and/or GAPDH were conducted for their molecular identification. The pathogenicity of the most representative Colletotrichum species was tested to olive fruits and to other hosts, such as almonds, apples, oleander, sweet oranges, and strawberries. In general, the phenotypic characters recorded were not useful to identify all species, although they allowed the separation of some species or species complexes. ITS and TUB2 were enough to infer Colletotrichum species within C. acutatum and C. boninense complexes, whereas ITS, TUB2, ACT, CHS-1, HIS-3, and GADPH regions were necessary to discriminate within the C. gloesporioides complex. Twelve Colletotrichum species belonging to C. acutatum, C. boninense, and C. gloeosporioides complexes were identified, with C. godetiae being dominant in Spain, Italy, Greece, and Tunisia, C. nymphaeae in Portugal, and C. fioriniae in California. The highest diversity with eight Colletotrichum spp. was found in Australia. Significant differences in virulence to olives were observed between isolates depending on the Colletotrichum species and host origin. When other hosts were inoculated, most of the Colletotrichum isolates tested were pathogenic in all the hosts evaluated, except for C. siamense to apple and sweet orange fruits, and C. godetiae to oleander leaves.