Slow sand filtration eradicates eucalypt clonal nursery plant pathogens from recycled irrigation water in Brazil

Abstract

Contaminated irrigation water constitutes one of the main sources of plant pathogens that can cause disease and lead to potentially significant production losses in forest nurseries. Recycling of contaminated irrigation water increases the risk of spreading diseases. The objective of this study was to evaluate a simple slow sand filtration treatment of irrigation water as a method for eradicating fungal and bacterial pathogens in eucalypt cutting nurseries. Pilot filter units were constructed from PVC pipes containing a 80 cm high layer of sand with grain size varying from 0.50 to 0.75 mm, drainage layers of 10 cm of fine gravel (4 mm) followed by a 15 cm layer of coarse gravel (8 mm), connected to a water outlet. The PVC pipe had space for a 150 mm water column above the sand layer and the filter had a flow rate of 100 to 300 L m -2 h -1 . Eradication of the bacterial pathogen Ralstonia solanacearum, and the fungal pathogens Cylindrocladium candelabrum and Botrytis cinerea through the use of the filter was evaluated. Detection of bacteria in filter-treated irrigation water was performed through the micro drop method followed by PCR of colonies, while fungal pathogens were detected using a castorbean leaf biological bait method. Evaluations were performed daily 35 times for R. solanacearum, 25 times for C. candelabrum and 18 times for B. cinerea during a period of 12 months. After the last evaluation period, samples from various depths of the sand layer in the filters were taken and analyzed for the presence of the plant pathogens. The slow sand filters were able to remove B. cinerea and C. candelabrum spores with 100% efficiency while eradication of R. solanacearum colonies reached up to 99.6%. Colonies of Trichoderma sp. were found predominantly on the all filter layers. The results of this study show that slow sand filters are efficient for recycled water in eucalypt nurseries, especially in eradicating fungal pathogens.

Diversity and potential impact of Calonectria species in Eucalyptus plantations in Brazil

“…Thus far however, the majority of the reports from Brazil focused on forestry crops, such as Pinus and Acacia ( Hodges and May, 1972 , Hodges et al., 1973 , Alfenas, 1986 , Dianese et al., 1986 , Novaes et al., 2012 , Alfenas et al., 2013a , Alfenas et al., 2013b ) and in particular on the epidemiology and disease control of Calonectria spp. associated with diseases of Eucalyptus in commercial plantations and nurseries ( Blum et al., 1992 , Mafia et al., 2008 , Mafia et al., 2009 , Graça et al., 2009 , Ferreira et al., 2012 , Alfenas et al., 2013c ).…”

FUNGOS ASSOCIADOS À MANCHA FOLIAR EM Eucalyptus benthamii Maiden et Cambage NA REGIÃO SUL DO BRASIL

“…Espécies de Cylindrocladium têm sido relatadas como agentes patogênicos em diversas culturas, inclusive florestais, tais como pinus e acácia (HODGES; MAY, 1972;HODGES et al, 1973;ALFENAS, 1986;DIANESE et al, 1986;NOVAES et al, 2012), e, em particular, no gênero Eucalyptus, associados as doenças em plantios comerciais e em mudas nos viveiros (BLUM et al, 1992;GRAÇA et al, 2009;MAFIA et al, 2009;FERREIRA et al, 2012;ALFENAS et al, 2013;SCHULTZ et al, 2015;REZENDE et al, 2017). Esse fungo é a fase anamórfica do gênero Calonectria e é a fase mais comumente encontrada na natureza como agente causal de várias doenças, sendo crucial para a identificação em nível de espécie (CROUS, 2002).…”

Integrated management of eucalyptus bacterial wilt in Sumatra, Indonesia.

“…For that reason, water, sand and tools used in the nursery are expected to be sterilized prior to planting of mother plants in order to avoid potential infections with Ralstonia inoculum. Pathogen free water can be obtained through sand ltration system combined with chlorination process (Ferreira et al 2012) and sterilization of tools can be done by means of thermal treatment at 85-90 o C for at least 30 sec (Ma a et al 2012). However, an issue experienced by nursery managers (author's personal information) is related to operationalization of steam sterilization currently used in most forestry clonal nurseries.…”