Investigation of Drought Intensity and Periodicity in South Texas using Chemical and Biological Records in Bat Guano Cores

Studies of bat guano deposits have indicated that chemical and isotopic variations recorded in the guano record can be used to examine historical variations in climate. Bracken Bat Cave in south-central Texas hosts a large bat colony that is thought to have inhabited the cave for many hundreds of years. Recent geophysical surveys suggest that guano deposits as thick as 108 ft (33 m) may be present in some areas of the cave. This study examined the potential use of the Bracken Bat Cave guano deposits to develop a robust proxy for climate change and drought history in south Texas. Approximately 24 ft (7 m) of guano core samples were collected from Bracken Bat Cave during three sampling campaigns in early 2016. The guano cores revealed distinct physical and compositional layering. For example, guano pellets along with insect and bone detritus enabled identification of more than twenty distinct layer sequences within a 9 ft (2.7 m) vertical section. Chemical, isotopic, and mineralogical analyses were conducted on sample isolates. Radiocarbon (14C) and stable isotopic data (2H/1H, 13C/12C, 15N/14N), along with other supporting chemical data, have been used to establish age and chemical signatures associated with core sample depths and stratigraphic layers. Contrary to initial expectations, the sampled areas appear to represent guano deposition over decades rather than centuries according to isotope data correlated with layer sequences, which are thought to represent annual cycles. The time frame of deposition can be correlated with historical local weather data. This allows evaluation of the utility of guano core in evaluating short-term and relatively recent weather patterns. The success of the correlation of chemical and isotopic variations to historical weather data of known periods of drought dictates whether longer guano core records may be used to ascertain frequency and duration of historical – and possible prehistorical – periods of drought that predate other conventional climate records

Use of biocontrol agents and botanicals in integrated management of Botrytis cinerea in table grape vineyards

BACKGROUND: There is increasing interest in the use of biological control agents (BCAs) and botanicals (BOTs) due to increasing awareness of the environmental and human health risks associated with synthetic plant protection products. The BCAs Bacillus subtilis strain QST713, Bacillus amyloliquefaciens strain D747 and Aureobasidium pullulans strains DSM14940 and DSM14941, and the BOTs Melaleuca alternifolia and terpenic extracts are proposed for the control of grey mould in vineyards. This study was aimed at evaluating their effectiveness in integrated crop management strategies and their outcomes in terms of the management of fungicide resistance and residues. RESULTS: In field trials carried out on table grapes in southern Italy, use of BCAs or BOTs alternately or mixtures of BCAs or BOTs with the succinate dehydrogenase inhibitor fungicide fluopyram showed efficacy of up to 96% against grey mould on bunches, comparable with the chemical reference strategy (up to 87%). By contrast, use of BCAs or BOTs (up to 11 sprays) alone was not effective (< 30%) under high disease pressure. The integrated use of BCAs or BOTs reduced the spread of succinate dehydrogenase inhibitor-resistant conidia, as well as fungicide residues in grapes. CONCLUSIONS: Spray schedules based on integration of BCAs or BOTs with fungicides are effective against grey mould and reduce the risk of fungicide resistance in B. cinerea and fungicide residues in grapes