Weeds as Potential Hosts for Fungal Root Pathogens of Watermelon

Abstract

Many watermelon (Citrullus lanatus) diseases are caused by soilborne pathogens in Brazil and worldwide. The goal of this study was to identify and quantify the frequency of phytopathogenic fungi associated with watermelon root rot and vine decline that were also present in the roots of weeds in the major watermelon production regions in the state of Rio Grande do Norte, Brazil. We collected root samples from 10 of the most prevalent weed species in 16 watermelon producing areas. The plants were identified and their frequencies in the fields were calculated. The fungi found in the weed roots were isolated and the main genera associated with watermelon vine decline were identified. We identified 13 weed species belonging to nine botanical families. The weed species with the highest frequencies found in the field were Amaranthus spinosus (25.0%), Trianthema portulacastrum (18.8%), Commelina sp. (18.8%), and Boerhavia diffusa (12.5%). The fungi Macrophomina, Rhizoctonia, and Monosporascus were isolated from the roots of the weed plants. While Macrophomina was isolated from 12 different types of plants, Rhizoctonia and Monosporascus were isolated from four and two different plant species, respectively.

Plant-Parasitic Nematodes Associated With Common Horticultural Weeds

“…Nevertheless, there is still no specific report mentioning the amount of dropped results caused by weed competition with the cultivated crops. The presence of weed in the horticultural land can indirectly be the alternative host for some pathogens, namely bacteria, fungi, viruses, and nematode (Sales Júnior et al, 2019). A. conyzoides can be an alternative host for Begomovirus (Leke et al, 2012).…”

GENETIC SIMILARITY OF Macrophomina pseudophaseolina ISOLATES ASSOCIATED WITH WEEDS IN THE BRAZILIAN SEMIARID REGION

“…Continuous cropping and expansion of planted areas without effective disease management increased the incidence and severity of numerous pathologies in producing fields in the Northeast region (SALES JÚNIOR et al, 2019). Root rot and vine declining (RRVD), caused by soilborne fungi species, limits melon production in the region (PORTO et al, 2019;SALES JÚNIOR et al, 2012).…”

Prevalent weeds collected from cucurbit fields in Northeastern Brazil reveal new species diversity in the genus Monosporascus

“…In addition to root pathogens, weeds also interfere with agricultural production, as they compete directly with the main crop for water, light and nutrients, as well as release allelopathic substances that inhibit plant development and serve as host of microorganisms (Lemessa & Wakjira, ; Sales Júnior et al, ; Soares et al, ). Recently, Rodrigues () and Sales Júnior et al () evaluated the occurrence of weeds as alternative hosts of root phytopathogenic fungi in cucurbit production areas in the Brazilian states of RN and CE, reporting 13 weed species as hosts of fungal root pathogens associated with vine decline of melon and watermelon such as Macrophomina phaseolina (Tassi) Goid. and Rhizoctonia solani Kühn.…”