Botrytis cinerea

Mahmoud, Mohannad, BenRejeb, Ines, Punja, Zamir K., Buirs, Liam & Jabaji, Suha, 2023, Understanding bud rot development, caused by Botrytis cinerea, on cannabis (Cannabis sativa L.) plants grown under greenhouse conditions, Botany 101 (7), pp. 200-231 : 213-214

Monitoring of Botrytis cinerea spore levels

A number of techniques have been described to obtain bioaerosol samples containing pollen and fungal spores, including those of Botrytis and other pathogens ( Jackson and Bayliss 2011; Mainelis 2020). The Hirst volumetric slit-type sampler ( Hirst 1952) was the first spore trap to be used in epidemiological studies. It allows for continuous sampling from 24 h to 7 days and is powered either by a main supply or a 12 V solar battery. It is characterized by high spore collection efficiency and can be used with PCR techniques for fungal identification ( Calderon et al. 2002; Neumeister-Kemp et al. 2004). This spore trap was used to collect spores of Botrytis cinerea from vineyards ( Oliveira et al. 2009; Rodríguez-Rajo et al. 2010; Fernandez-Gonzalez et al. 2012; Martínez-Bracero et al. 2019; Cortiñas Rodríguez et al. 2020). The spore trap is sensitive to particle size, wind speed, and loss of power ( Neumeister-Kemp et al. 2004).

The Portable Rotorod sampler is another widely used method to detect a range of airborne fungal spores ( Crisp et al. 2013). It is easy to manipulate but the impaction surface can be overloaded by pollen or dust and the sampling period is limited ( Chandelier et al. 2021). The most likely time for release of Botrytis cinerea spores is between 8 a.m. and 1: 30 p. m. ( Boff et al. 2001). Therefore, several Rotorod runs of 15 min duration are needed to obtain representative spore collection results ( Boff et al. 2001). These samplers have been used to monitor spread of Botrytis cinerea before the appearance of disease symptoms in strawberry, grapevines, and tomato crops ( Boff et al. 2001; Decognet et al. 2009; González-Fernández et al. 2020).

The Burkard volumetric spore trap (capacity of 10 L/min), which can record for 7 days continuously, was used to trap conidia of Botrytis cinerea in tomato and strawberry fields ( Chastagner et al. 1978; Xu et al. 2000; Gioulekas et al. 2004). This method was also used to collect Botrytis cinerea spores in greenhouses planted to rose ( Boulard et al. 2008) and geranium ( Hausbeck and Pennypacker 1991) crops.

The cyclonic spore sampler is an easy-to-use device that can handle a small number of airborne spores and requires less labor for counting spores. However, spores can stick to the collection cylinder, requiring rinsing between samples. This device was used in a laboratory setting to compare Botrytis cinerea spore density in the air versus on filters ( Cook et al. 2002).

The Air-O-Cell is a spore trap with high collection efficiency for small particles designed for indoor environments. This was used to detect Botrytis cinerea in air samples ( Aizenberg et al. 2000; Codina et al. 2008). Different filter materials can be used for different sample analyses, but high intersample variability and low uniformity of particle deposition on the filters were reported.

The Coriolis air sampler is an innovative solution dedicated to outdoor monitoring of airborne spores and pollen grains. It was used to detect Botrytis cinerea from outdoor (compost and air) and controlled environment conditions by using filtration protocols ( Carvalho et al. 2008; Mbareche et al. 2019). Airborne particles are collected in a liquid medium using filtration and centrifugation protocols that allow rapid analysis by PCR to identify fungal species.

Microtiter immunospore trapping device represents another trapping technique used to detect fungal spores ( Kennedy et al. 2000) that involves enzyme-linked immunosorbent assay (ELISA). The technique was used to detect Botrytis cinerea in greenhouses containing Brussels sprouts. The implementation of spore trapping devices to monitor spore populations of Botrytis cinerea in cannabis greenhouses has not been undertaken.