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Summary. Some weeds have parasitic lifestyles, causing severe problems in agriculture. These plants include Phelipanche ramosa (L.) Pomel (branched broomrape). Green house and nursery trials were carried out to assess control of P. ramosa using organic extracts from 14 plant species. The parameters recorded were counts of living and dead tubercles of P. ramosa and fresh weights of living tubercles. Organic extract of Olea europea reduced lengths of germ tubes during P. ramosa seed germination, and extracts of Bidens bipinnata and Dittrichia viscosa reduced production and development of the parasite’s tubercles, with very encouraging results in reducing seed germination rates. This research provides knowledge insights on the potential use of plant secondary metabolites to limit spread of P. ramosa, addressing an increasing challenge for organic crop production. [ABSTRACT FROM AUTHOR]

Root parasitic weeds of the genera Orobanche and Phelipanche (commonly named broomrapes) are responsible for enormous yield losses of several crops all around the world. Traditional weed management methods, including among others the use of herbicides, soil fumigation and solarization, and mechanical, agronomic or physical methods, may have limits of use or can provide a modicum of control. Difficulties in controlling parasitic weeds are due to both the enormous number of seeds produced by each plant that can remain viable for many years, even in the absence of a host, and to the unique physiological and biological properties of the parasite. Although long considered a suitable and promising approach, biological control, in particular the use of microbial organisms or compounds stimulating or inhibiting seed germination, has had no commercial success and no products have reached the market. This article provides a quick overview of the bioherbicide approaches attempted until now, briefly discussing the causes of the failures and the possibility to improve biocontrol agents' effectiveness. Indeed, despite the failures, the 'bioherbicide' approach deserves renewed interest in light of the enormous scientific and technological progress made in past years, which offers new chances of success. © 2023 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Araujia hortorum is a perennial vining plant species native to South America. It was introduced into many countries for ornamental and medicinal purposes as well as for its edible fruits, but it has become highly invasive, generating severe environmental problems. Biological control using bioherbicides and natural compounds is an interesting control option. The pathogenic fungus Ascochyta araujiae, isolated from infected leaves of A. hortorum, could be considered as a potential biocontrol agent. Its ability to produce bioactive metabolites was studied. The organic extract of the fungal culture filtrates showed interesting phytotoxic activities consisting of clearly visible necrotic symptoms (0.5–1 cm in diameter) in the punctured leaves. Thus, it was purified; this afforded three main metabolites. These were chemically and biologically characterised: one proved to be a new pentasubstituted dihydrofuro[3,2-b]furan-2(5H)-one, named araufuranone (1). The others were the already known fungal metabolites neovasinin and 2,4-dihydroxy-6-hydoxymethylbenzaldehyde (2 and 3). The structure of araufuranone was determined using spectroscopic methods (essentially 1D and 2D 1H and 13C NMR and HR ESIMS spectra); its relative configuration was assigned by a NOESY spectrum. To the best of our knowledge, araufuranone is the first example of a naturally occurring compound showing that carbon skeleton. Assayed by a puncture, araufuranone proved to be weakly active on the leaves of Diplotaxis sp. and Sonchus sp.; the other two metabolites were even less toxic. Tested on cress, compounds 2 and 3 were able to partially inhibit rootlet elongation whereas araufuranone was almost inactive. [ABSTRACT FROM AUTHOR]

Since 1987, several cytochalasins were isolated from Phoma exigua var. heteromorpha, the causal agent of foliar blight disease of oleander (Nerium oleander L.), and chemically and biologically characterised. During the purification process of a large-scale production of cytochalasins A and B, necessary to continue the study on their anticancer activity, a metabolite having a different carbon skeleton compared to that of cytochalasans, was isolated. It was identified as terpestacin, a well-known toxic fungal stestertepenoid, isolated for the first time from P. exigua var. heteromorpha, by spectroscopic investigation (essentially 1D and 2D 1H and 13C-NMR and ESI MS) and optical methods in comparison with the literature data. Terpestacin and some its derivatives (including a natural one, fusaproliferin) were prepared and tested for their biological activity. Terpestacin and fusaproliferin had some inhibitory effects on seed germination of Phelipanche ramosa, whereas none of the compounds caused phytotoxic effects on weed leaves. [ABSTRACT FROM AUTHOR]

Ophiobolin A is a secondary phytotoxic metabolite produced by some pathogenic fungal species responsible for severe plant diseases, considered to play a role in disease development and symptom appearance. Herein we investigated whether the phytotoxic activities of ophiobolin A against weed species could be improved by nanoencapsulation. Given the rapid natural degradation of the compound, it was hoped that nanoencapsulation would prolong the phytotoxic effects or enhance the bioactivity, thus leading to improved weed control capabilities. This article presents an assessment of the effectiveness of encapsulated ophiobolin A on 11 commonly found weed species, compared to the pure ophiobolin, to the particle alone, and a combination of mixed particles and ophiobolin A, by applying the solution droplets to both intact or injured leaf surface, on the adaxial or abaxial side. The bioassays showed the improved efficacy of the encapsulated ophiobolin, and the need for leaf lesions to diffuse the particles into the tissues. [ABSTRACT FROM AUTHOR]