One of the main barriers for conventional farmers converting to organic production is weed control An experiment was set up to evaluate the efficacy of three mechanical weed control methods tine weeder spoon weeder and interrow hoe (only in the beans (Phaseolus vulgaris)) in four organically grown crops In borage (Borago officinalis) weed dry matter (DM) was reduced by 41 in tineweeded plots but there was no treatment effect on crop DM or yield There was no treatment effect in the peas (Pisum sativum) In linseed (Linum usitatissimum) mechanical weeding reduced weed DM by 41 and resulted in a 28 increase in crop yield In beans weed DM was reduced by 74 in mechanicallyweeded plots but the tine weeder reduced crop DM compared with the other mechanical weeding treatments

An RNA derivative (pSPT 18.15) of Jeffreys' 33.15 human minisatellite core sequence was used to probe DNA from individuals of the peach-potato ( M yzuspersicae) and grain ( avenae) aph and reproducible quantities of DNA (M. persicae = 0.90 + 0.19 pg DNA individual-1; avenae = 1.50 + 0.30 pg DNA individual-1) were extracted from individuals by whole-body homogenization to produce complex multi-locus DNA fingerprints. Profiles contained 19.5 + 2.4 (M. and 14.8+ 1.2 (S. avenae) fragments per individual, mainly within the 0.6-6.6 kb range, and exhibited marked endonucleasespecific variations in complexity. Individuals from six clones of S. avenae found to be monomorphic at 11 putative allozymic loci could be distinguished using their DNA fingerprint profiles. Fingerprints from a clone of M. persicae were stable over nine parthenogenetic generations showing the absence of major genetic rearrangements ('endomeiosis') during apomictic parthenogenesis. The demonstration that sequences homologous to human minisatellite regions are both present and polymorphic in an invertebrate, coupled with the ability to characterize clones from individuals yielding small quantities of DNA show that genetic fingerprinting should be especially valuable for monitoring the diversity and dynamics of clonal animals in the field.

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The performance of the mustard beetle, Phaedon cochleariae (F.), treated orally and topically with a range of foliar fungicides was assessed using data on several life-history variables. For some compounds a significant effect on the insect's developmental period and/or fecundity was demonstrated. P. cochleariae larvae were shown to exhibit repellency towards host plants treated with some of the fungicides. Phaedon cochlearzae wurde oral und topikal mit einigen Blattfungiziden behandelt, urn eine Reihe von Entwicklungsparametern zu untersuchen. Fur einige Praparate konnte ein signifikanter Einfluf? auf 518 A . /. Cherry, N . W. Sotherton m d S. D. Wratten die Entwicklungszeit der Larven und/oder die Fekunditat nachgewiesen werden. Bei einigen Fungiziden zeigte sich eine repellente Wirkung auf P. cochleariae.