A late frost occurred in the Southland region of New Zealand in November 1995 when many winter wheat (Triticum aestivum L.) crops were at early grain fill, and resulted in a large number of insurance claims for frost damage. In this study, frost damage was characterised. Spikes in affected crops were sharply tapered from a point half to two-thirds from their bases. Grains were as much as 80% lighter in upper parts of affected spikes. Overall yield losses as a result of frost of between 13 and 33% were calculated in affected crops. Grains were sectioned and examined with a scanning electron microscope. Whereas in healthy grains, the layers making up the pericarp and testa were compressed, in frosted grains these layers comprised loosely compressed and unstructured networks of cells. The aleurone layer was less ordered in frosted than in normal grains, and was not always readily distinguished from the starchy endosperm. Rehydration of frosted grains was accompanied by expansion of pericarp and testa cells, whereas little cell expansion occurred in normal grains. Blisters were common in frosted grains, where the outer layers were detached from the remainder of the pericarp.

The durum wheat industry in New Zealand is based in South Canterbury supplying the local Timaru Milling Company with specialist grains for the making of pasta and pasta-related products. 'Waitohi' durum wheat has been bred as a high yielding - high quality replacement to the standard durum cultivar 'Tara'. Regional trials indicate a small yield advantage over 'Tara' with improved pasta processing characteristics and a higher colour grading in the milled and processed product.

Hexaploid derivatives of wild emmer wheat (Triticum dicoccoides Koern.) developed at the Volcani Research Center, Israel, were grown at Lincoln, New Zealand and tested for a number of milling and baking quality parameters and for gliadin and high molecular weight (HMW) glutenin protein composition. The average protein content of most of the derivatives was higher than that of the bread wheat standards (12.9 v. 11.4070) and about half showed an increase in loaf volume. Protein content, dough strength, and baking quality were related to the presence of specific protein components. In particular, superior quality was found to be closely associated with the presence of the HMW glutenin subunits 2*, 5 + 10, and 7 + 8. This agrees with results for European wheats.

Four wild emmer derivatives were compared with two standard bread wheats for their ability to accumulate grain nitrogen after foliar urea sprays at heading. The highest levels and total contents of grain nitrogen and flour protein were found in emmer derivatives. Sampling during grain development showed that the movement of nitrogen into the grain from other parts of the plant was greatest and more firmly directed towards the grain in the emmer derivatives. Grain size did not decrease significantly as grain nitrogen levels and total nitrogen contents and flour protein increased with increasing urea application rates. Baking scores also increased with increasing urea application rate but correlations with the nitrogen parameters were consistent only within individual lines and not across all lines.

Successful cultivation of flue-cured tobacco requires particular soil types and climatic conditions. The only area in New Zealand where these conditions are found is in and around the Motueka Valley, where, on about 6000 acres, half the country's tobacco requirements are grown.

Verticillium dahliae isolated from tomatoes in Canada induced severe symptoms of verticillium wilt on inoculated tobacco plants in field plots at Macdonald College, Québec. The disease has not been reported on tobacco in Canada, but is limiting tobacco production in infested districts in New Zealand. Climatic conditions and some cultural practices are comparable in Québec and possibly other tobacco-growing areas in Canada with those in the tobacco region of New Zealand. It is probable that verticillium wilt will occur in tobacco fields in Canada, particularly in Québec, but its effects may be minimized by careful field sanitation and appropriate farm practices.

Summary Green, chlorotic, and necrotic tissue from leaves of tobacco plants naturally infected with Verticillium dahliae were prepared for study with the electron and light microscopes. Isolations were made and the fine structure of the fungus compared in vivo and in vitro. It was found to be similar in both environments. Degenerating hyphae, intrahyphal hyphae, endospores, and structure of the microsclerotia were observed in cultured isolates. The fungus was seen in the xylem elements, but not in the adjacent parenchymatous tissue. Unidentified bodies were observed in the intercellular spaces of green and chlorotic mesophyll tissue and within chlorotic and necrotic mesophyll cells. In many cases these bodies were in the process of passing through the cell walls. Increased site and number of plastoglobuli were observed in chloroplasts just before their degeneration and this change may be associated with chlorosis.

The percentage infection with potato virus Y in 19 tobacco crops in the Nelson district at the end of the 1964-65 season varied from 0-720/0. with an average of 260/0. Virus Y markedly reduced the weight and leaf area of tobacco plants. The quality of the cured leaf was also adversely affected, and the nor-nicotine content was higher and the reducing sugars were lower in infected leaves. Infection of tobacco plants with virus Y did not affect the germinaton of seed.

Sixty-six strawberry clover (Trifolium fragiferum L.) clones were studied for factors affecting low seed-setting. Most of the clones proved to be self-incompatible but some set relatively high percentages of seed autogamously. The evidence supports the hypothesis that this clover is predominantly a cross-pollinating species. Bombus terresiris worker bees were found to be efficient pollinators of strawberry clover.

Tobacco root and stem systems were studied to determine their relative importance in resistance to Verticillium dahliae Kleb. Three cultivars, the most susceptible and resistant of which differed widely in resistance to the disease, were grafted so that the stems and roots were united in all possible combinations. The act of grafting lowered resistance in the more susceptible cultivars. The rootstocks of the most resistant cultivar markedly reduced symptoms in the susceptible scions grafted to them, and the stems of the resistant cultivar had more resistance than the stems of the susceptible ones. A method of estimating the amount of susceptibility of the different graft combinations at different periods of growth is described. The data most closely fitted a hypothetical model in which 74 percent of the resistance in all varieties at all stages of growth was contributed by the root system, the remainder corning from the stem.