Oidium perseae-americanae sp. nov. on avocado

Oidium perseae-americanae is described causing powdery mildew on avocado (Persea americana) in New Caledonia and Brazil.

First record of Aecidium sp. on Marsdenia sp. in Australia

Aecidium sp. (Pucciniaceae) on Marsdenia sp. is reported for the first time from Australia.

The distribution and spread of citrus canker in Emerald, Australia

Citrus canker is a disease of citrus and closely related species, caused by the bacterium Xanthomonas citri subsp. citri. This disease, previously exotic to Australia, was detected on a single farm [infested premise-1, (IP1). IP is the terminology used in official biosecurity protocols to describe a locality at which an exotic plant pest has been confirmed or is presumed to exist. IP are numbered sequentially as they are detected] in Emerald, Queensland in July 2004. During the following 10 months the disease was subsequently detected on two other farms (IP2 and IP3) within the same area and studies indicated the disease first occurred on IP1 and spread to IP2 and IP3. The oldest, naturally infected plant tissue observed on any of these farms indicated the disease was present on IP1 for several months before detection and established on IP2 and IP3 during the second quarter (i.e. autumn) 2004. Transect studies on some IP1 blocks showed disease incidences ranged between 52 and 100% (trees infected). This contrasted to very low disease incidence, less than 4% of trees within a block, on IP2 and IP3. The mechanisms proposed for disease spread within blocks include weather-assisted dispersal of the bacterium (e.g. wind-driven rain) and movement of contaminated farm equipment, in particular by pivot irrigator towers via mechanical damage in combination with abundant water. Spread between blocks on IP2 was attributed to movement of contaminated farm equipment and/or people. Epidemiology results suggest: (i) successive surveillance rounds increase the likelihood of disease detection; (ii) surveillance sensitivity is affected by tree size; and (iii) individual destruction zones (for the purpose of eradication) could be determined using disease incidence and severity data rather than a predefined set area.

Citrus Information Kit. Agrilink, your growing guide to better farming guide

Each Agrilink kit has been designed to be both comprehensive and practical. As the kits are arranged to answer questions of increasing complexity, they are useful references for both new and experienced producers of specific crops. Agrilink integrates the technology of horticultural production with the management of horticultural enterprises. REPRINT INFORMATION - PLEASE READ! For updated information please call 13 25 23 or visit the website www.daf.qld.gov.au This publication has been reprinted as a digital book without any changes to the content published in 1997. We advise readers to take particular note of the areas most likely to be out-of-date and so requiring further research: see detailed information on first page of the kit. Even with these limitations we believe this information kit provides important and valuable information for intending and existing growers. This publication was last revised in 1997. The information is not current and the accuracy of the information cannot be guaranteed by the State of Queensland. This information has been made available to assist users to identify issues involved in the production of citrus. This information is not to be used or relied upon by users for any purpose which may expose the user or any other person to loss or damage. Users should conduct their own inquiries and rely on their own independent professional advice. While every care has been taken in preparing this publication, the State of Queensland accepts no responsibility for decisions or actions taken as a result of any data, information, statement or advice, expressed or implied, contained in this publication.

Austropleospora osteospermi gen. et sp nov and its host specificity and distribution on Chrysanthemoides monilifera ssp rotundata in Australia.

Hendersonia osteospermi was found for the first time in Australia on leaf spots of the introduced invasive plant Chrysanthemoides monilifera ssp. rotundata (bitou bush) in coastal regions of New South Wales. Pathogenicity tests on species from 11 tribes in the family Asteraceae, demonstrated that H. osteospermi caused severe necrosis on leaves and stems of C. monilifera ssp. rotundata and its congener C. monilifera ssp. monilifera (boneseed). Small necrotic spots also developed on Osteospermum fruticosum and Dimorphotheca cuneata in the Calenduleae and on Helianthus annuus (sunflower) in the Heliantheae. None of the other plant species tested developed leaf spots, although H. osteospermi was re-isolated from senescent leaves of Cynara scolymus (globe artichoke) in the Cynareae and Vernonia cinerea in the Vernonieae. Single ascospores from ascomata of a Pleospora-like fungus found on diseased stems of bitou bush produced H. osteospermi in culture, which proved the anamorph/teleomorph connection. The ITS region of both a single-ascospore isolate and a single-conidium isolate were sequenced and found to be identical. The taxonomic status of H. osteospermi is re-examined and Austropleospora osteospermi gen. et sp. nov. is described as its teleomorph based on morphology, host range tests and DNA sequence analysis. The potential of A. osteospermi for the biological control of bitou bush and boneseed in Australia is discussed.

Ramichloridium spp. on Musa in northern Queensland: introducing Ramichloridium ducassei sp. nov. on leaf streaks of Ducasse banana.

The fungi associated with tropical leaf speckle diseases of banana (Musa spp. and cultivars) in northern Queensland were examined from fresh leaves and herbarium specimens. Ramichloridium biverticillatum was predominantly found associated with leaves of Cavendish banana (Musa acuminata cv. Cavendish) and a new species, R. ducassei was found associated with dark brown streaks on leaves of Ducasse banana (Musa acuminata x balbisiana cv. Pisang awak). A key is provided for all of the species of Ramichloridum that are known to occur on Musa.

CSIRO lead National Citrus Scion Breeding Program

National Citrus Scion Breeding Program.

Protecting the Australian citrus industry from HLB (greening) disease

Protecting the Australian citrus industry from HLB (greening) disease.

National Citrus Triploid Breeding

This project advances commercially desirable citrus selections that have resilient seedlessness. It builds on existing expertise and develops germplasm resources in the utilisation of interploid crossing for the production of new triploid hybrids with outstanding fruit quality. Advanced germplasm will progress toward commercialisation with fruit displays, and the production of a final generation of trees for semi-commercial plantings. At the opposite end of the breeding spectrum, new triploid hybrids will be produced. Growers will see triploid citrus from their national breeding project for the first time, providing a window on future new varieties that will emerge from the pipe-line of germplasm that has been developed through past project investment.

Introduction, establishment, and potential geographic range of Carmenta sp. nr ithacae (Lepidoptera: Sesiidae), a biological control agent for Parthenium hysterophorus (Asteraceae) in Australia

Parthenium (Parthenium hysterophorus L.), a major weed causing economic, environmental, and human and animal health problems in Australia and several countries in Asia, Africa, and the Pacific, has been a target for biological control in Australia since the mid-1970s. Nine species of insects and two rust fungi have been introduced as biological control agents into Australia. These include Carmenta sp. nr ithacae, a root feeding agent from Mexico. The larvae of C. sp. nr ithacae bore through the stem-base into the root where they feed on the cortical tissue of the taproot. During 1998-2002, 2,816 larval-infested plants and 387 adults were released at 31 sites across Queensland, Australia. Evidence of field establishment was first observed in two of the release sites in central Queensland in 2004. Annual surveys at these sites and nonrelease sites during 2006-2011 showed wide variations in the incidence and abundance of C. sp. nr ithacae between years and sites. Surveys at three of the nine release sites in northern Queensland and 16 of the 22 release sites in central Queensland confirmed the field establishment of C. sp. nr ithacae in four release sites and four nonrelease sites, all in central Queensland. No field establishment was evident in the inland region or in northern Queensland. A CLIMEX model based on the native range distribution of C. sp. nr ithacae predicts that areas east of the dividing range along the coast are more suitable for field establishment than inland areas. Future efforts to redistribute this agent should be restricted to areas identified as climatically favorable by the CLIMEX model.

Host Susceptibility of Citrus Cultivars to Queensland Fruit Fly (Diptera: Tephritidae)

Citrus crops are considered to be relatively poor hosts for Queensland fruit fly, Bactrocera tryoni (Froggatt), as for other tephritid species. Australian citrus growers and crop consultants have reported observable differences in susceptibility of different citrus cultivars under commercial growing conditions. In this study we conducted laboratory tests and field surveys to determine susceptibility to B. tryoni of six citrus cultivars [(Eureka lemon (Citrus limon (L.) Osbeck); Navel and Valencia oranges (C. sinensis (L.) Osbeck); and Imperial, Ellendale, and Murcott mandarins (C. reticulata Blanco)]. The host susceptibility of these citrus cultivars was quantified by a Host Susceptibility Index, which is defined as the number of adult flies produced per gram of fruit infested at a calculated rate of one egg per gram of fruit. The HSI was ranked as Murcott (0.083) > Imperial (0.052) ≥ Navel (0.026) ≥ Ellendale (0.020) > Valencia (0.008) ≥ Eureka (yellow) (0.002) > Eureka (green) (0). Results of the laboratory study were in agreement with the level of field infestation in the four citrus cultivars (Eureka lemon, Imperial, Ellendale, and Murcott mandarins) that were surveyed from commercial orchards under baiting treatments against fruit flies in the Central Burnett district of Queensland. Field surveys of citrus hosts from the habitats not subject to fruit fly management showed that the numbers of fruit flies produced per gram of fruit were much lower, compared with the more susceptible noncitrus hosts, such as guava (Psidium guajava L.), cherry guava (P. littorale Raddi), mulberry (Morus nigra L.), loquat (Eriobotrya japonica (Thunb.) Lindl.), and pear (Pyrus communis L.). Therefore, the major citrus crops commercially cultivated in Australia have a relatively low susceptibility to B. tryoni, with Eureka lemons being a particularly poor host for this tephritid fruit fly.

Omnidemptus affinis gen et sp. nov., teleomorph of Mycoleptodiscus affinis sp. nov

Omnidemptus is described as a new monotypic genus of ascomycetes and O. affinis isolated from leaves of Panici effusi var. effusi in Queensland, Australia, is shown to have as its anamorph a new species of the hyphomycete genus Mycoleptodiscus, M. affinis.

Cochliobolus heliconiae sp nov (Ascomycota)

A new species of Cochliobolus, C. heliconiae, is described and illustrated. The species is heterothallic and ascomata were produced in pure culture using two isolates of its Bipolaris anamorph, also described as new, obtained from lesions on Heliconia spp. in northern Australia.

Paliphora intermedia sp nov from Australia

Paliphora intermedia sp. nov. (Hyphomycetes) from unidentified leaf litter collected in Queensland, Australia is described and compared with the two other species in the genus.

Sphaerophragmium quadricellulare sp nov (Mycota, Uredinales) on Acacia in Australia, with brief notes on some related rust genera

A telial rust on leaves of Acacia pennata ssp. kerrii from Cape York Peninsula is described as Sphaerophragmium quadricellulare sp. nov. No other spore stages have been observed. Brief notes on other related rusts occurring in Australia are given.