Tag: crops

New pathogen threatens fennel yield in Italy

A new fungal genus and species Ochraceocephala foeniculi causes fennel yield losses of about 20-30% for three different cultivars. It damages the crops with necrotic lesions on the crown, root and stem.
International research group makes the first step in handling the new fennel disease by publishing their paper in the open-access journal Mycokeys.

A new fennel fungal disease caused by a new genus and species – Ochraceocephala foeniculi, was observed for the first time in 2017 on 5% of the “Apollo” fennel cultivar grown in the sampled localities in Catania province, Italy. Now, it has spread to 2 more cultivars: “Narciso” and “Pompeo”, causing crop losses of around 20-30%. The new pathogen damages the fennel with necrotic lesions on the crown, root and stem.

Fennel, a crop native in arid and semi-arid regions of southern Europe and the Mediterranean area is massively used as a vegetable, herb and seed spice in food, pharmaceutical, cosmetic and healthcare industries with Italy taking the world-leading production. It is an important and widely cultivated crop in Sicily (southern Italy).

Symptoms caused by Ochraceocephala foeniculi on fennel plants
Symptoms caused by Ochraceocephala foeniculi on fennel plants
Credits: Dalia Aiello
License: CC-BY 4.0

Worldwide, fennel crops are affected by several fungal diseases. In Italy, amongst soilborne diseases, there have been reports of brown rot and wilt caused by Phytophthora megasperma and crown rot caused by Didymella glomerata.

International research group, led by Ms. Dalia Aiello from the University of Catania, made the first step in handling the new fennel disease by identifying the causal agent obtained from symptomatic plants and publishing the results of their research in the open-access journal Mycokeys.

In order to understand the origin of the causal agent, scientists collected 30 samples during several surveys in the affected areas in Sicily, and studied the consistently grown fungal colonies from symptomatic tissues.

“The fungal species obtained from symptomatic tissues was identified based on morphological characters and molecular phylogenetic analyses of an ITS-LSU-SSU rDNA matrix, resulting in the description of the fennel pathogen as a new genus and species, Ochraceocephala
foeniculi,”

shares Dr. Dalia Aiello.

According to the pathogenicity tests, O. foeniculi causes symptoms on artificially inoculated plants of the same cultivar. Preliminary evaluation of fennel germplasm, according to the susceptibility to the new disease, shows that some cultivars (“Narciso”, “Apollo” and “Pompeo”) are more susceptible and some are less susceptible (“Aurelio”, “Archimede” and “Pegaso”), but this is a subject yet to be confirmed by additional investigations. More studies are required in order to plan further effective disease management strategies.

Holotype of Ochraceocephala foeniculi
Credits: Mr. Hermann Voglmayr
License: CC-BY 4.0

“On the basis of the disease incidence and severity observed in the field, we believe that this disease represents a serious threat to fennel crop in Sicily and may become a major problem also to other areas of fennel production if accidentally introduced,”

concludes Dr. Dalia Aiello.
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Original source: Aiello D, Vitale A, Polizzi G, Voglmayr H (2020) Ochraceocephala foeniculi gen. et sp. nov., a new pathogen causing crown rot of fennel in Italy. MycoKeys 66: 1-22. https://doi.org/10.3897/mycokeys.66.48389

Parasite vs. Invader: New endoparasitoid wasp can save the Dominican Republic economy

While biocontrol agents come in different shapes, often taking a lot of time for scientists to research, test and produce, natural ones always seem to be the better option. Now that Drs. Taveras and Hansson have discovered a new parasitoid wasp species in the Dominican Republic, they might have not only met the worst natural enemy for a widely spread invasive pest corrupting a large part of the essential pigeon pea crops. They are likely to have found a whole new field for investigation into the potential weapons against the eradicator of up to 76% of the essential crop. Their study is available in the open access Journal of Hymenoptera Research.

The find of this new gregarious endoparasitoid wasp, called Pediobius cajanus, is also the first time representative of this genus has been retrieved from the Asian fly. This invasive pest is estimated to destroy a huge part of the pigeon pea crops, a culture which is an essential food source for tropical America, a large part of the export and even has medicinal value. Therefore, the new species is very important not only in terms of the exploration of the biodiversity in Latin America, but also in economical sense.

Even when treated regularly with insecticides, the Asian fly manages to corrupt as much as 27% of the Dominican pigeon pea crops, a previous study shows. Although a precise figure of the damage cannot be provided due to large variations between localities and the impossibility of tracking the whole span of the pea cultivation areas, there is the case of the town of Rancho Los Vargas, Puerto Plata, where in 2012 the loss of the culture reached 76%.

On the other hand, the new wasp species was found to kill an average of 25% of the Asian fly larvae in the researched areas. In comparison, the previously known enemies of the pest are accountable for only 2%. This is why the scientists are now proposing the new species as a biocontrol agent.

In conclusion, the authors suggest that the parasitoid wasp is likely distributed across a much larger area. They believe that the new species could also be found over the entire island of Hispaniola, on neighbouring islands in the Caribbean and even in the tropical parts of the mainland in the Americas. Its record and distribution both call for a further investigation into the potential implementation of the wasp in controlling the Asian fly.

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Original source:

Taveras R, Hansson C (2015) Pediobius cajanus sp. n. (Hymenoptera, Eulophidae), an important natural enemy of the Asian fly (Melanagromyza obtusa (Malloch)) (Diptera, Agromyzidae) in the Dominican Republic. Journal of Hymenoptera Research 45: 41-54. doi: 10.3897/JHR.45.4964