The Effects of Formulation on Imidacloprid Dissipation in Grapes and Vine Leaves and on Required Pre-Harvest Intervals under Lebanese Climatic Conditions

In this study, imidacloprid, a systemic insecticide, currently having a specified European Commission MRL value for vine leaves (2 mg kg−1), was applied on a Lebanese vineyard under different commercial formulations: as a soluble liquid (SL) and water dispersible granules (WDG). In Lebanon, many commercial formulations of imidacloprid are subject to the same critical good agricultural practice (cGAP). It was, therefore, important to verify the variability in dissipation patterns according to matrix nature and formulation type. Random samplings of grapes and vine leaves were performed starting at 2 days until 18 days after treatment. Residue extractions were performed according to the QuEChERS method and the analytical determination using liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS). The SL formulation yielded significantly higher initial deposit than the WDG formulation on grapes and vine leaves. The formulation type did not significantly affect the dissipation rates; the estimated half-lives in grapes and vine leaves were 0.5 days for all imidacloprid formulations. No pre-harvest intervals were necessary on grapes. PHIs of 3.7 days for the SL formulation and 2.8 days for the WDG formulation were estimated on vine leaves. The results showed that the type of formulation and the morphological and physiological characteristics of the matrix had an effect on the initial deposits, and thus residue levels, but not on the dissipation patterns.

Degradation of the insecticides fipronil and cypermethrin in green onions (Allium fistulosum) and mustard greens (Brassica juncea)

Pesticide dissipation on foods like vegetables, fruits, and cereals is one of the most concerning aspects in pesticide toxicology as it involves risks to human health and food safety. In light if this, a laboratory-scale study was conducted for two separate systems, green onions (Allium fistulosum) and mustard greens (Brassica juncea),in order to identify the dissipation of fipronil and cypermethrin, two commonly used insecticides, under a tropical climate. After the pesticide application, vegetable samples from these microcosms were collected each day for 7 days to measure fipronil and cypermethrin (n=3) residues. The analytical method was validated and showed repeatability and trueness. The decay equations fit well to first-order kinetics with a correlation coefficient of R2>0.93 and p<0.0005. The calculated half-life values of fipronil were 2.9 d for green onions and 3.2 d for mustard greens while those of cypermethrin were, respectively, 4.5 d and 3.2 d. To meet the maximum residue levels (MRL) of fipronil (0.02 mg/kg) and cypermethrin (0.7 mg/kg) on vegetables, the estimated pre-harvest intervals should be updated to 23 d and 7.5 d, respectively.

Effects of Machine-Harvest Interval on Fruit Quality of Fresh Market Northern Highbush Blueberry

Machine harvesting blueberry (Vaccinium sp.) alleviates labor costs and shortages but can reduce fruit quality. Installation of softer catching surfaces inside modified over-the-row harvesters (modified OTR) and adjusting harvest intervals may improve fruit quality and packout. The objective of this study was to determine the effect of harvest interval on fruit quality of fresh market northern highbush blueberry (Vaccinium corymbosum L.) harvested using a modified OTR. ‘Liberty’ blueberry bushes were harvested by hand or using a modified OTR at 3-, 10-, and 14-day intervals in 2019 and at 7-, 11-, and 14-day intervals in 2020. Hand-harvested ‘Liberty’ had greater packout and firmness than machine-harvested fruit. Machine harvesting at the 3-day interval in 2019, and the 14-day interval in 2020 reduced packout from 70–80% to 60% and 54%, respectively. In 2019, machine harvesting at a 3-day interval overall resulted in fruit with greater firmness, higher titratable acidity (TA), and lower total soluble solids (TSS) and SS/TA, compared to other harvest intervals. In 2020, the 7-day machine-harvest interval had a greater TA and lower TSS/TA, compared to the 11- and 14-day intervals. Overall, modified OTR machine-harvest intervals can be extended to 10–11 days for fresh market northern highbush cultivars such as ‘Liberty’ grown in northwest Washington.

Agronomic Evaluation of the Results of Selection within Early Maturing Dactylis glomerata Germplasm

Selection from novel orchardgrass (Dactylis glomerata L.) germplasm sources resulted in the development of an early maturing orchardgrass population. Fifty-eight families comprise this population and were evaluated under frequent and infrequent harvest intervals at Lewiston and Millville, UT, field locations during 2013 and 2014. The objective of this study was to characterize the performance of the individual families when compared with the check cultivars ‘Icon’, ‘Paiute’, and ‘Potomac’. Across the locations and harvest intervals, individual families produced greater herbage dry mass and nutritive value than the check cultivars. Only for maturity (cv. Paiute) did one of the included commercial checks possess a trait value among the statistically greatest for all families. Twenty-two half-sib families were among the families with the statistically earliest maturity, and between three and eight families were among the families with the statistically greatest trait values for herbage dry mass, crude protein, in vitro true digestibility, neutral detergent fiber, and water soluble carbohydrate concentration. Overall, based on the performance of its component families, this early maturing orchardgrass population exhibited potential for developing improved cultivars for both frequent and infrequent harvest management.

Plant Growth and Morphological Characters of Sonchus arvensis L. from Different Chicken Manure Rates and Harvest Intervals with Ratooning Practices

Sonchus arvensis L., commonly known as perennial sow thistle, field milk thistle, among other names, is a weedy species that has medicinal values. Belongs to the Daisy family (Asteraceae), S. arvensis has a rosette form and it can be harvested more than once. The determination of harvest interval for ratoon of S. arvensis is necessary because ratooning can save time to produce the consecutive plant biomass, but the second harvest must be conducted at the correct time as it will determine the quantity and quality of leaves. As source of herbal medicine, cultivation of S. arvensis with organic fertilizer is preferred, and determination of organic fertilizer rates is also important for ratooning. The purpose of the study was to evaluate the plant growth response and yield with different chicken manure rates and different harvest intervals. The field experiment was conducted at IPB experimental station in Cikarawang, Darmaga Bogor, Indonesia. The study used a randomized complete block design with different manure rates (0, 7, 14, 21 ton.ha-1) and various harvest intervals (6, 8, and 10 weeks after the first harvest) as treatments. The results showed that for the first harvest, the effect of chicken manure rates was linear almost on all variables. For the ratoon (second harvest), manure rate of 14 ton.ha-1 (for first harvest) added with 4 ton.ha-1 (after first harvest) was enough for leaf production. The results indicate that ratoon should be harvested at 10 weeks after the first harvest to obtain the highest yield. The interaction between manure rates and harvest interval was not significant for growth variables of the second harvest.

The Effects of Different Rates of Chicken Manure and Harvest Intervals on the Bioactive Compounds of Bitter Leaf (Vernonia amygdalina Del.)

Bitter leaf (Vernonia amygdalina Del.) is a valuable functional vegetable and traditional medicinal plant in many tropical countries including Indonesia. Bitter leaf is commonly used to remedy hypertension and diabetes among Indonesian people. The leaf extract comprises bioactive compounds such as sesquiterpene lactones, steroid glycosides, and flavonoids. Despite its growing market demand, there is insufficient data on agronomic practice in order to obtain optimum yield with high bioactive compounds. The experimental design used was a randomized complete block design with two factors namely chicken manure rates (0, 2.5, 5, and 7.5 kg per plant) and harvest intervals (2 and 3 months). There was a significant difference in fresh and dry weights of leaves, chlorophyll a and b, carotenoids, nitrogen concentration, anthocyanins, and flavonoids among different manure treatment. The highest concentration and production of bioactive compounds on the bitter leaf was found on the highest treatment of 7.5 kg chicken manure per plant. The harvest interval of three months significantly increased fresh and dry weights of leaves, concentration of anthocyanins, phosphorus, and potassium, uptake of phosphorus and potassium, and production of anthocyanins and flavonoids. Cultivation using chicken manure with frequent period of pruning can enhance the production of biomass as well as secondary metabolites in bitter leaf.

Agronomic Evaluation of the Results of Selection within Late-Maturing Dactylis glomerata Populations

Selection from novel orchardgrass (Dactylis glomerata L.) germplasm sources resulted in the development of a late-maturing orchardgrass population. This population comprises 58 families that were evaluated with 5 commercial cultivars under frequent and infrequent harvest intervals at two Cache County, UT, USA field locations during 2013 and 2014. The objective of this study was to characterize the performance of individual families when compared to check cultivars Intensive and Latar. Across locations and harvest intervals, individual families produced greater herbage dry mass and nutritive value than the check cultivars did, i.e., up to 12% greater herbage dry mass than that of the highest check, Intensive, and 1% (neutral-detergent-fiber digestibility) to 14% (water soluble carbohydrates) greater forage quality than that of the corresponding highest check cultivar. However, there were substantial genotype-by-environment interactions between families and locations, but not harvest intervals. Because of this, results were analyzed across harvest intervals but within locations. Within each location, there were families that possessed similar or greater maturity, herbage dry mass, in vitro true digestibility, and neutral-detergent-fiber digestibility at both locations. Overall, on the basis of the performance of its component families, this late-maturing orchardgrass population exhibited potential for developing improved cultivars.

DETERMINATION OF PHYTOCHEMICALS FROM FRESH FRUITS OF FIG (Ficus carica L.) AT DIFFERENT MATURITY STAGES

The natural and ubiquitous production of figs throughout Turkey makes it one of the most important centers of fig genetic resources. The current study aims to determine the most important phytochemical ingredients of a local variety of fig (Ficus carica L.) collected from the natural habitats in the province of Kahramanmaras at different harvest intervals in 2018. The fruit samples were assayed for various metabolites such as phenolic compounds, total phenols (TP), total flavonoids (TF), total anthocyanins (TA) and total antioxidant capacity (TAC). The results showed that epicatechin (7.809 mg/100 g FW) was dominant phenolic compound in the fruits of this variety, followed by myricetin (2.632 mg/100 g FW), kaempferol (2.396 mg/100 g FW) and quercetin (0.655 mg/100 g FW). The average values obtained for TP, TF, TA, and TAC were found to be 135.71 mg GAE/100 g FW, 188.20 mg/100 g FW, 54.65 ml/L, and 14.34 DPPH%, respectively. There were also observed significant differences in total polyphenolic, flavonoid, anthocyanin content, and the antioxidant capacity at different harvest periods. The current findings indicate that the fig variety explored has a high antioxidant activity and is rich sources of anthocyanins and phenolic content. This study provides valuable information about the health benefits of figs endorsed by the phytochemical characteristics.