Effects of cow urine in the agroecological management of insects and witches' broom (Moniliophtora perniciosa Stahel Aime & Phillips-Mora) in cacao crops (Theobroma cacao L.)

Witches' broom (Moniliophtora perniciosa Stahel Aime Phillips-Mora) was first reported in the state of Bahia (Brazil), in 1989, in areas of cacao cultivation, where it immediately became the most important disease of this culture, responsible for marked losses in production, mainly by weakening the plants and causing leaf area reduction, leading even to the death of the adult plant. After several years of dropping cacao production in the southern region of Bahia, producers have renovated their hopes for farming by adopting practices that favor increments in productivity, such as stand renewal using productive, self-compatible genetic material that is more resistant to this disease, thus enhancing the cultural management of cacao in agroforestry systems. In order to combat this disease, farmers have resorted to pesticides; however, their indiscriminate use has led to the contamination of workers and the environment, which is increasingly unbalanced and creating resistance to the fungus. Alternative methods to control this disease are already being tested by the producers themselves, who have perceived improvements in their crops and in their quality of life when using them, mainly since they are natural, cheap, and easily accessible, as is the case of cow urine pulverization. In this study, we evaluated the application of cow urine at different concentrations, with five treatments and four repetitions each, using a completely randomized design. The results showed that lactating cow urine at concentrations of 0.5%, 1.0%, and 1.5% was as efficient as the pesticide used as a control in the experiment, simulating conventional treatment. However, no significant differences in results were observed when using the Tukey test at 5% probability.

Occurrence, development and natural enemies of Pemphigus spyrothecae (Homoptera, Pemphigidae)

In 2001, galls were analysed of Pemphigus spyrothecae Pass. taken in one- to three-week intervals from Populus nigra and P. nigra var. italica at 4 localities in Brno. Fundatrices matured in the first half of June and during the first half of summer produced about 50 offsprings. Virgines produced about 10 offsprings which grew up in winged sexuparae. The winged individuals started to occur in galls from the beginning of August. In galls with intact development, on average 500 aphids developed. Galls with intact development on P. nigra var. italica reached larger average dimensions and contained at least by 4% more aphids than galls on P. nigra. About 5% of fundatrices died already in the 1st instar and other 3 to 6% in higher instars by the beginning of reproduction. At localities under investigation, 7.5 to 39.0% of galls on P. nigra and 3.9 to 13.7% of galls on P. nigra var. italica were occupied by the fly Leucopis puncticornis Meig. (Chamaemyiidae). About 24.3 to 32.2% of galls on P. nigra and 23.3 to 49.3% of galls on P. nigra var. italica were occupied by the bug Anthocoris minki Dohrn (Anthocoridae). Hover flies Heringia heringi (Zett.) and Pipiza festiva Meig. (Syrphidae) killing aphids in 3.8 to 30.4% of galls on P. nigra and 6.5 to 6.8% of galls on P. nigra var. italica were an important regulator. In August (i.e. at the beginning of the formation of winged sexuparae), the majority of galls opened through primary slit-shaped or oval emergence holes. A part (7.8 to 19.5%) of galls with so far intact development, however, remained closed and all aphids contained in them died. Diseases (particularly mycoses) often participated in the accelerated dying of aphids. The effect of mortality factors on the gall size differentiation was evaluated in details. The galls do not cause any leaf area reduction. In the case of mass outbreak, they decrease decorativeness of poplars in street alleys. In August and September, liquid excrements fall out from the galls (honeydew) polluting the environment in villages and housing estates.

Effect of Minicutting Length and Leaf Area Reduction on Growth and Nutritional Status of Eucalypt Propagules

Significant improvements to the technique of minicutting Eucalyptus clones have been reported in the literature. However, despite these recent efforts, studies addressing the proper size of minicuttings and the reduction of leaf area have not been well explored. Thus, the present study had the objective of evaluating the effects of the length of the minicuttings and the leaf area reduction on the growth and nutritional condition of Eucalyptus urophylla during propagation. The experiment was conducted for 90 days in the Plantar Reforestation Co. Nursery in the municipality of Curvelo, MG, using a randomized block design with 4 replicates in a 4×2×2 factorial arrangement. The effects of 4 lengths of minicuttings (4, 6, 8, and 10 cm), 2 levels of leaf area reductions (0 and 50%), and 2 commercial clones were studied. The length of the minicuttings and the reduction of leaf area did not affect the nutritional status of the leaves, nor did the length affect the quality of the plants at the age of 90 days. The results indicate that it is unnecessary to reduce the leaf area for Eucalyptus propagation.

Influence of leaf area reduction on clonal production of eucalyptus seedlings

Clonal production of eucalyptus seedlings has made considerable progress in recent years. Significant developments have taken place in irrigation and fertilization systems as well as in management of clonal miniorchards. However, the proportion of leaf area in stem minicuttings remains almost the same as that used in macrocutting systems. This work aimed to evaluate the effect of leaf area reduction on seedling production of eight eucalyptus clones. The experiment was conducted over a period of 105 days using a randomized block design and three replicates in an 8 x 4 factorial arrangement, with eight clones and four leaf reduction levels (0%, 25%, 50% and 75%). Variables evaluated included height, root collar diameter, shoot and root dry matter and relationships between these variables. Experimental results demonstrated that clones behaved differently as to leaf reduction and that the 0% reduction level can be adopted in most clones being evaluated.

Game browse and its impact on selected grain crops

This work presents the results of a survey that studied simulated plant browsing by herbivores. In 2004–2006, winter wheat, spring barley, and maize field trials were founded in order to monitor the impact of different levels of defoliation (leaf area reduction) on the yield and grain quality. The defoliation was carried out by means of mechanical removal of plant parts in the early growth stages. Selected qualitative parameters were determined in the harvested grain of wheat and barley. Statistically significant influence of leaf area reduction (LAR) on grain yield (decrease by 4–14%) was found only in maize in 2004. No statistically significant influence of the leaf area reduction on thousand grain weight (TGW) was found in any of the studied crops. The leaf area reduction in barley did not affect grain characteristics; however, it had a statistically significant influence on the quality of wheat grain. Moreover, wheat reduction statistically significantly increased the falling number (by 29–39 s) and decreased SDS test values (by 8–9 ml).

The effect of leaf area reduction on the yield and quality of sugar beet (Beta vulgaris L. var. altissima Döll).

The yield of sugar beet is directly affected by LAI (leaf area index) and values of LAD (leaf area duration). The integral leaf area plays, except for other factors, an important role during the damage or reduction of leaf apparatus. There are many sources of leaf damage: natural disasters (hailstorm), diseases, pests (including game browsing) etc. The intensity of the root production and quality differs in relation to the growth stage of the damage plant. The aim of this study was to evaluate the extent of losses in the root yield and the quality of sugar beet upon gradual reduction of the leaf area. Two diploid varieties Monza and Compact were used in the small-plot trials conducted in years 2004 to 2006 (in the experimental station Žabčice – maize production region, zone K2, average altitude 184 m, soil type was classified as gley fluvisoil, soil is medium heavy to heavy, clay-loam to loam type). The leaf area was manually reduced by 25% and 50% at BBCH 18–19 growth phase (8–9 leaves unfolded). The results were statistically evaluated by analysis of variance and testing by Tukey test (at the significance level α = 5%). Reduction of the leaf area was reflected on the decrease of the root yield by 1 to 10% depending on the year of harvest. In addition, the stressful state of the plants after defoliation resulted in the decrease of the yield of polarization sugar per hectare, namely by 0.45 to 1.66 t.ha–1. In 2005, the leaf area reduction caused a rise of the α-amino nitrogen content. The rise in the potassium and sodium cations content caused by the leaf area reduction also increased the sugar content in the treacle (by 0.1 to 0.16%). The increasing leaf area reduction lead to decreasing of yield of polarization sugar. However, this descent was statistically significant in harvest year 2006 only.

The effect of fire severity and salvage logging traffic on regeneration and early growth of aspen suckers in north-central Alberta

Density and growth of trembling aspen (Populus tremuloides Michx.) were measured in the first two years following wildfire to determine the effects of: 1) fire severity and 2) salvage logging damage on sucker regeneration. Results indicate that stand leaf area was not affected by fire severity, although the greatest number of suckers was produced following high severity burns. In contrast, plots with the highest level of machine disturbance in the salvage-logging study had 60% fewer suckers compared to the non-trafficked plots. These suckers tended to be smaller and had less leaf area than the non-trafficked plots, resulting in a stand leaf area reduction of up to 75%. This suggests that salvage logging could have a negative impact on the future growth and productivity of regenerating aspen stands. Key words: trembling aspen, regeneration, suckering, leaf area, wildfire, fire severity, salvage logging, machine traffic