Leaves, orchard

The pesticides methyl and ethyl parathion were determined in run-off water er preconcentration on XAD-2. This allowed analyses of these compounds at the parts per billion level (497). Parathion and paraoxon obtained from leaf extracts and orchard soil have also been determined (492). The separation of 30 carbamate pesticides by RPC has been described (493). Various modes of postcolumn fluorometric detection of carbamate insecticides have been reported including post-colun)n reaction between o-phthalaldehyde and methylamine, a carbamate hydrolysis... 

Insects This method has received little attention as a means of combating weeds in citrus. Habeck (1977) showed that insects could be used against largeleaf lantana and stranglervine. A number of leaf-mining beetles have been used successfully in Australia and Hawaii to control largeleaf lantana, which is a major weed in Florida citrus orchards (Tucker and Singh, 1983). 

Predatory mites are the most important beneficials in apple orchards. They are about 0.4 mm in size, long, drop-shaped and milky white to orange-red in colour. They tend to congregate around the central rib on the underside of the leaf. 

The beech leaf-mining weevil has a rather different life cycle. In this case the weevil overwinters as a beetle. The eggs of the beech leaf-mining weevil are laid on the leaves of beech trees. It is only occasionally found in orchards. 

In the case of the beech leaf-mining weevil, it is particularly important to monitor orchards near woodland. 

Rose proliferation and stunting as well as rose leaf curl and shoot dieback symptoms in rose cultivars were associated with aster yellows phytoplasmas (AY, 16SrI-B). It was also found, that two rose cultivars, with shoot proliferation or flower proliferation symptoms were infected by phytoplasma classified to apple proliferation group (16SrX-A) (Kaminska and Sliwa, 2004). Jarausch et al. (2001) reported the occurrence of European stone fruit yellows phytoplasma (16SrX-B), Candidatus phytoplasma prunorum and rubus stunt (16SrV-E), in asymptomatic Rosa canina plants surrounding peach orchards. 

Jarausch, W., Jarausch-Wehrheim, B., Danet, J.L., Broquaire, J.M., Dosba, F., Saillard, C. and Gamier, M. (2001). Detection and identification of European stone fruit yellows and other phytoplasmas in the surroundings of apricot chlorotic leaf roll-affected orchards in southern France. European Journal of Plant Pathology, 107 209-217. 

Figure 4. Results for the determination of copper in an organic matric (Orchard Leaf) by isotope dilution.

Thus [Cu] was thus calculated to be 11.3 ppm for this orchard leaf sample which was NBS certified as 12 ppm. The sampling procedure required only a few seconds for each of the measurements, and only three scans or less are needed for this type of procedure. Precision is typically of the order of +0.5% and combined with the system s speed the technique is obviously suitable for multielement quantitative determinations, and those applications requiring high sample throughput. 

Table 3.8 summarises the deposition of spray on soil surface underneath apple trees in orchards. When spraying apple trees in full leaf, spray deposition on the ground is on average 25% (18-35%), (Heer and Schut, 1986 Crum and de Heer, 1991 Porskamp et al., 1994a, 1994/ Ganzelmeier and Osteroth, 1994 Heijne et al., 1995). Spray deposition on the soil is not significantly different between axial and cross-flow sprayers, but tunnel sprayers (Zande et al., 1998) can decrease soil deposition by 50%. When trees are not in leaf, spray... 

Table 3.9 Spray deposition (% dose) on orchard-tree leaf surface (apple) for different periods during the growing season, and different spray techniques...

Figure 3.10 Spray deposition on leaf tissue and ground related to LAI in orchard spraying...

Benomyl and the other benzimidazole fungicides are toxic to earthworms (Stringer and Wright, 1973) and may seriously disturb the earthworm population, for instance, in orchards, so that the leaf litter is not removed. Some benzimidazole fungicides (thiabendazole and mebendazole) may be used as anthelmintica. 

The distribution of the preparation over the surface of a treated leaf depends on the application rate. For example, in spraying a cherry orchard with a 0.8% suspension of Sevin with an application rate of 565 liter/ha, all of the liquid falling on the plant leaves remains there. When the application rate is doubled, part of the suspension runs off, and the density of the deposit on the bottom side of the leaves is 1.3 times that on the top side. The addition of Plyac (a surfactant) made it possible to reduce the insecticide application rate by improving the adhesion. 

Our study revealed a strong negative association between leaf lifespan and Pmax (Fig. 6A) and, to a lesser extent, negative associations between leaf lifespan and SLA (Fig. 6B) and Nl (Fig. 6C). Study species included various plants sampled from each of four simulated biome mesocosms (tropical rainforest, savannah-orchard, dry thorn-scrub, and sandy beach). There were, in some cases, significant differences in leaf-level characteristics between plants from different mesocosms which explains much of the plot scatter in Fig. 6 (not shown). However, the overall trends were quite robust even without accoimting for these mesocosm differences. 

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