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Dartmouth, Canada

'Hamlin' sweet orange trees on 'Carrizo' citrange and 'Swingle' citrumelo rootstocks were treated weekly with a commercial extract of the brown seaweed Ascophyllum nodosum at 5 and 10 mL[1]L-1 as either a soil drench or foliar spray. Half of the trees in each treatment were subjected to drought stress [irrigated at 50% of evapotranspiration (ET)], whereas the other half remained fully irrigated (100% ET). Drought stress reduced shoot growth and leaf photosynthesis but increased root and total plant growth relative to the amount of water applied, thus increasing whole plant water use efficiency. Trees treated with seaweed extract and drought-stressed had significantly more total growth than untreated drought-stressed trees for both rootstocks. The maintenance of growth by the seaweed extract under drought stress conditions was unrelated to photosynthesis. However, the seaweed extract treatment did have a significant effect on plant water relations. Soil drench-treated trees had more growth and higher stem water potential than foliar-treated or control trees after 8 weeks of drought stress. These results indicate that seaweed extract may be a useful tool for improving drought stress tolerance of container-grown citrus trees.

Thrips cause damage to vegetables, fruits, and flowers and are found worldwide. They directly damage crops by feeding, vectoring viruses, and may also cause respiratory and skin irritation to field workers. Effectively managing thrips and mites with non-toxic materials has proven to be one of the most challenging aspects of pest control. A commercial extract from the brown seaweed Ascophyllum nodosum, reduced avocado thrips (Scirtothrips perseae) numbers by 68% compared to the control, in field-grown 'Hass' avocado trees. This reduction in thrips number was not significantly different from reduction due to abamectin treatment; the most common chemical control for thrips in avocados. In addition, there were 87% fewer colonies of Persea mites (Oligonychus perseae) per leaf in the A. nodosum extract (ANE)-treated trees compared to the control and the ANE-treatment was not significantly different from the abamectin standard. The following year there was no thrips pressure due to environmental conditions, however, ANE extract again reduced Persea mite colonies compared to the control. ANE extract applications resulted in significantly fewer thrips nymphs and Persea mite colonies on avocados under light pest pressure.

da Silveira L.C.I.,Federal University of Parana | Mattos P.,Federal University of Parana | Mogor A.F.,Federal University of Parana | Daros E.,Federal University of Parana | And 2 more authors.
Idesia | Year: 2015

In order to improve the growth of sugarcane plantlets, this study examined the effects of a seaweed (Ascophyllum nodosum) extract on shoot and root dry mass accumulation of plantlets budding from segments taken from apical, medial and basal parts of culms of the RB867515 variety. The experiment was a 3 × 2 factorial (three culm sections × kelp extract applied at 2.0 l.ha-1 and control) at the Sugar Cane Research Station at the Federal University of Paraná, Brazil. Results showed improvement in shoot and root dry mass accumulation in plantlets budding from the basal part of culms following treatment with the A. nodosum kelp extract. © 2015, Universidad de Tarapaca. All rights reserved.

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