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This article provides information on new or uncommon plant diseases and pests discovered in Great Britain. The first is the development of stem and inflorescence galls on yarrow caused by nematode Anguina millefolii. The infested yarrow plants were originally supplied from Starcross, Devon. The second reported incident was the spread of tomato ringspot virus in North America. The virus was initially cultured in Chenopodium amaranticolor and purified by phosphate buffer-butanol extraction. The isolate caused severe symptoms in several glasshouse crop plants including lettuce, tomato and cucumber and in several ornamental plants. Another fungal disease caused by coniothyrium fragariae was also discovered during an investigation of a necrotic condition in strawberry crown in Scotland. It appears to be the first record of C. fragariae in Great Britain.

Both the 'oat race' and 'giant race' of Ditylenchus dipsaci (Kühn) Filipjev infest field beans (Vicia faba L.) in Britain and the infested seed sometimes produced is an important means of spreading them. The large soil populations, especially of the 'oat race', that build up in beans from infested seed may damage subsequent crops of beans, peas, sugar beet and especially susceptible oats. Bean seed for sowing should be saved from uninfested fields only. Only oat cultivars resistant to D. dipsaci should be grown in crop rotations that include beans. [ABSTRACT FROM AUTHOR]

This article provides information on the chemical treatment of quarantined banana stocks infested with plant parasitic nematodes. Helicotylenchus dihystera, Radopholus similis and Meloidogyne spp. were found infesting quarantined banana stocks held at the Royal Botanic Gardens, Kew, England. Dipping peeled sets in nematicidal chemicals and applying dibromochloropropane at intervals to the growing plants in pots checked the infestations and promoted healthy root growth.

About 10% of the ware-sized tubers from a 1990 potato crop were found to have dry rot. The affected tubers had well defined circular patches of dry rot, either with the tuber surface depressed and cracked, or with deep, open cavities where the tuber surface had disintegrated. The rotted tissues contained large numbers of the stern and bulb nernatode, Ditylenchus dipsaci. This is the first recorded case in the UK; dry rot of potato tubers is usually caused by the potato tuber nematode D. destructor. [ABSTRACT FROM AUTHOR]

Examines the nematodes, Paratrichodorus renifer Siddiqi and Tylenchorhynchus claytoni Steiner, associated with azaleas in England. Origin of the nematodes; Host range; Characteristics of the nematodes.

This article describes a study concerning the effects of two soil types on the diffusion of soil sterilants. Differences in soil type and structure were analyzed (1)mechanically, (2) by moisture characteristic and (3) by measuring the rate that nitrogen diffused when artificially introduced into the soil. The sandy clay loam contained more sand than the loam soil, less silt and organic matter; and at pF 17 it had more empty pore space through which gas diffused more rapidly.

Describes the fungal hosts for the chrysanthemum nematode, Aphelenchoides ritzemabosi. Number of plant species attacked by the nematode; Basic features of the nematode; Occurrence of the nematode in temperate regions; Consideration of the worm as an obligate parasite of plants.

This article describes new weed hosts for the giant race of Ditylenchus dipsaci Filipjev. In April 1981, stunted and distorted plants of annual red dead-nettle and perennial white dead-nettle were found growing at Honeybourne in Worcestershire, England in a field infested with the giant race of D. dipsaci Filipjev. Nematode infestation was probably introduced to the site with seed of field bean in 1978. Samples of both Lamium species were heavily infested with all stages of D. dipsaci.

The polymerase chain reaction (PCR) was used to amplify a fragment of the ribosomal DNA (rDNA) from species and undescribed populations of Aphelenchoides and Ditylenchus angustus. The PCR primers used were based on conserved sequences in the 18S and 26S ribosomal RNA genes of Caenorhabditis elegans. In C. elegans, these primers amplify a 1,292 base pair (bp) fragment, which consists of the two internal transcribed spacers and the entire 5.8S gene. Amplification products from crude DNA preparations of 12 species and populations of Aphelenchoides and from D. angustus ranged in size from approximately 860-1,100bp. Southern blots probed with a cloned ribosomal repeat from C. elegans confirmed the identity of these amplified bands as ribosomal fragments. In addition to the differing sizes of the amplified rDNA fragments, the relative intensity of hybridization with the C. elegans probe indicated varying degrees of sequence divergence between species and populations. In some cases, amplified rDNA from the fungal host was evident. Storage of A. composticola at - 45 C for 2 years did not affect the ability to obtain appropriate amplified products from crude DNA preparations. Amplified rDNA fragments were cut with six restriction enzymes, and the restriction fragments produced revealed useful diagnostic differences between species and some undescribed populations. These results were consistent with previous studies based on morphology and isoenzymes. Three undescribed populations of Aphelenchoides were found to be different from all the species examined and from each other.