Effect of Foliar Spray of Nano Silver and Organic Fertilizer (Algastar) and Salicylic Acid on Some Morphological Characteristics and Carbohydrate Content in (Helianthus annuus L.)

Intercropping is a major production strategy in the tropics. Sesame (Sesamum indicum L.) and sunflower (Helianthus annuus L.) are two resilient oilseed crops of high economic potential with contrasting growth and morphological characteristics, which may make them suitable candidates for intercropping. Two field trials were conducted during the late cropping season (July–November) of 2018 and 2019 at Abeokuta, Nigeria, to evaluate the effects of organic fertiliser application and varying the introduction date of sunflower into sesame fields on intercrop productivity and efficiency. Sunflower was sown at 0, 10 and 20 days after sowing (DAS) of two varieties of sesame. On average, mixtures that involved either sesame variety with sunflower interplanted at 0 or 10 DAS plus fertiliser application showed a high land-equivalent ratio of >1.00 (biological efficiency), high land-equivalent coefficient of >0.25 (intercrop compatibility), and high economic efficiency in terms of monetary advantage index and sesame yield equivalent. Weight of sesame capsules per plant increased significantly (P < 0.05) following application of organic fertiliser in both years. Similarly, aboveground plant weight of sesame was significantly (P < 0.05) enhanced irrespective of the date of introducing sunflower into sesame fields in both years. Sesame grain yield (543.4–636.5 kg/ha) during the wetter late season of 2019 compared favourably with mean values from Africa (473.5 kg/ha) and the world (512.3 kg/ha). Organic fertiliser application significantly (P < 0.05) enhanced sesame grain yield in both years. Delaying introduction of sunflower until 20 DAS of sesame resulted in significantly (P < 0.05) lower sunflower head weight and achene weight per head and depressed sunflower grain yield in both years. Therefore, mixtures of both sesame varieties with sunflower introduced at 0 or 10 DAS and with organic fertiliser applied achieved high intercrop productivity and land-use efficiency, and are hereby recommended for cultivation under humid tropical conditions.

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Residues of neonicotinoid insecticides in pollen and nectar from model plants1

Journal of Environmental Horticulture ◽

10.24266/0738-2898-35.1.24 ◽

2017 ◽

Vol 35 (1) ◽

pp. 24-34 ◽

Cited By ~ 3

Author(s):

Richard S. Cowles ◽

Brian D. Eitzer

Keyword(s):

Helianthus Annuus ◽

Foliar Spray ◽

High Rate ◽

Helianthus Annuus L ◽

Insecticide Residues ◽

Systemic Insecticides ◽

Agronomic Crops ◽

Application Rates ◽

Ornamental Crops ◽

Toxic Concentrations

Abstract Systemic insecticides used for ornamental horticulture crops can protect all portions of a plant with long-lasting effects. However, they may be hazardous to pollinators foraging on contaminated nectar or pollen. Two model plant cultivars were chosen based upon their ability to produce large quantities of pollen or nectar, enabling examination of the level of nectar or pollen contamination (e.g., insecticide “residues”) following insecticide treatments, rather than for the need or advisability to treat these plants in production nurseries or the landscape with systemic insecticides. These plants were sunflower (Helianthus annuus L. ‘Taiyo') for pollen, and swamp milkweed (Asclepius incarnata L. ‘Ice Ballet') for nectar. Plants were treated at labeled nursery rates with imidacloprid, dinotefuran, or thiamethoxam via foliar spray or soil drench at various times before bloom. Insecticide residues from pollen and nectar varied based upon application method, insecticide, and rate. Assuming that residues should be considered hazardous when they exceed 25 parts per billion (ppb) for nectar or 100 ppb for pollen, potentially bee-toxic concentrations of insecticide in sunflower pollen only followed high-rate drench treatments. Toxic concentrations of neonicotinoids were found in milkweed nectar when applied either as a drench or as a foliar spray up to six weeks before bloom. Label directions for nursery and greenhouse plants permit very high application rates relative to agronomic crops. These high rates can create hazardous conditions for pollinators, and should be avoided for ornamental crops that are highly attractive to bees. Index words: sunflower (Helianthus annuus L.); swamp milkweed (Asclepius incarnata L.); dinotefuran; imidacloprid; thiamethoxam; pollinator; systemic insecticides. Chemicals used in this study: dinotefuran (Safari 20 SG); imidacloprid (Xytect 2F); thiamethoxam (Flagship 25 WG). Species used in this study: sunflower (Helianthus annuus L.); swamp milkweed (Asclepius incarnata L.).

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