The double-stranded DNA genome of Blueberry red ringspot virus (BRRV), a member of the family Caulimoviridae, was cloned and sequenced. The genome organization and relationships of the 8303 nt sequence revealed BRRV to be a tentative member of the genus that has been provisionally named "Soybean chlorotic mottle-like viruses", rather than a member of the genus Caulimovirus, in which it had been placed previously. Insertion of the putative 35S promoter homolog of BRRV into promoterless constructs carrying the UidA (beta-glucuronidase) gene resulted in high-level transient expression from cranberry and stable expression from transgenic tobacco. Sequences of 5'-RACE clones derived from transcripts from transgenic tobacco were consistent with the map position of the promoter.

A B S T R A C TStrawberries are highly sensitive to deterioration by microbial decay after harvest and Botrytis cinerea is one of the most common diseases that infect them. Previous work has reported successful extension of strawberry shelf life through the use of chlorine dioxide (ClO 2 ) gas treatments. In this study, California strawberries purchased at retail stores were treated with continuously generated ClO 2 gas over concentrations ranging from 0.01 to 5.0 mg/L for durations ranging from 7 to 1000 min to determine how ClO 2 gas impacts fungal mortality and fruit quality as a function of treatment concentration, treatment duration, and ClO 2 absorption by the fruit. Repeated measures and Gompertz models were used to infer on the efficacy of the ClO 2 gas, and a novel method was used to quantify the ClO 2 absorption by fresh produce. It was found that ClO 2 gas treatments have minimal effect at delaying the onset or growth rate of Botrytis cinerea for treatments followed by incubation at 4 or 22 C even when corrected for natural variability of Botrytis cinerea presence among batches of strawberries, indicating that treatments are not sufficient for shelf-life extension.

Botrytis cinerea on grapes causes bunch rot at both pre- and post-harvest stages, where losses can reach up to 100%. Chemical control primarily relies on the prophylactic use of site-specific fungicides. Repeated applications of these products raise the risk of fungicide resistance development in B. cinerea populations, in which can result in disease control failures. To determine the extent of resistance, B. cinerea isolates were collected from grape clusters in the northwest and southwest grape growing regions of Michigan in 2014 (n = 115) and 2018 (n = 125). These isolates were phenotyped using discriminatory doses of 8 fungicides to determine the levels of resistance. Fungicide resistance increased from 2014 to 2018 mostly affecting the active ingredients fenhexamid, fluopyram, and iprodione. B. cinerea isolates resistant to multiple fungicides were detected in 2014 and 2018, with a higher frequency of resistance in 2018. TaqMan real time PCR has been developed to detect B. cinerea fungicide resistance to fenhexamid and to differentiate the erg27 F412S/I/V alleles. The assay was tested for sensitivity, specificity, and reproducibility on purified DNA and infected grape tissue samples. Our data provide essential information to growers about the efficacy for B. cinerea control using the available botryticides. Further, the developed fenhexamid markers will be transferred to diagnostic clinics to assist growers in the management of bunch rots before resistance related control failures occur.

Anthracnose fruit rot of blueberries caused by Colletotrichum acutatum is a serious problem in humid blueberry-growing regions of North America. In order to develop a disease prediction model, environmental factors that affect mycelial growth, conidial germination, appressorium formation and fruit infection by C. acutatum were investigated. Variables included temperature, wetness duration, wetness interruption and relative humidity. The optimal temperature for mycelial growth was 26°C, and little or no growth was observed at 5 and 35°C. The development of melanized appressoria was studied on Parafilm-covered glass slides and infection was evaluated in immature and mature blueberry fruits. In all three assays, the optimal temperature for infection was identified as 25°C, and infections increased up to a wetness duration of 48 h. Three-dimensional Gaussian equations were used to assess the effect of temperature and wetness duration on the development of melanized appressoria (R 2 = 0Á89) on Parafilm-covered glass slides and on infection incidence in immature (R 2 = 0Á86) and mature (R 2 = 0Á90) blueberry fruits. Interrupted wetness periods of different durations were investigated and models were fitted to the response of melanized appressoria (R 2 = 0Á95) and infection incidence in immature (R 2 = 0Á90) and mature (R 2 = 0Á78) blueberry fruits. Additionally, the development of melanized appressoria and fruit infection incidence were modelled in relation to relative humidity (R 2 = 0Á99 and 0Á97, respectively). Three comprehensive equations were then developed that incorporate the aforementioned variables. The results lay the groundwork for a disease prediction model for anthracnose fruit rot in blueberries.

The genus Trifolium consists of eight sections including Vesicaria, which might be termed the bladder clovers. Two centers of diversity within the section are the north Mediterranean region and the eastern part of Irano‐Taranian region. The two species of agricultural importance in the USA are the perennial strawberry clover (T. fragiferum L.) and the annual persian clover (T. resupinatum L.). The overall objectives of these investigations were to determine the evolutionary relationships among Vesicaria taxa, and to provide data for future possible interspecific hybridizations leading to improvement of the cultivated species of the USA as well as to authenticate the validity of nomenclature for taxa existing in the USDA world seed collection maintained at the University of Kentucky. To accomplish these objectives, breeding system, crossing and morphological relationships among eight taxa were examined in greenhouse investigations. Close similarities were indicated for two annual allogamous species, T. resupinatim and T. clusii. These species were considerably different from two other annual species, T. tomentosum L., and T. bullatum Boiss, both of which are autogamous. Among the perennial group, T. fragiferum appeared quite closely related to T. neglectum C.A.M. The other two perennial species, T. physodes Stev. ex M.B. and T. tumens Stev. ex M.B. are genetically isolated and morphologically different from each other and other species of the section. Shriveled seeds were produced from crosses of some species indicating the possiblity of producing interspecific hybrids via embryo rescue and tissue culture. Gene transfer among the species indicated as closely related by crossing investigations should be rather easy.