Florida Broadleaf Research Articles

Irrigation Scheduling for Small-Scale Crops Based on Crop Water Content Patterns Derived from UAV Multispectral Imagery

A timely irrigation schedule for small-scale farms is imperative for ensuring optimum crop production in the wake of drought and climate change. Owing to the large number of irrigated small-scale farms that grow different crops across all seasons in the Mutale River catchment, this study sought to develop irrigation scheduling for these crops for sustainable water utilization without compromising crop yields. Unmanned aerial vehicle (UAV) images were utilized as the base from which crop water content patterns were derived. A total of four (4) spectral vegetation indices, viz, the Greenness Normalized Difference Vegetation Index (GNDVI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Red-Edge Index (NDRE), and Optimized Soil-Adjusted Vegetation Index (OSAVI), were generated to characterize crop types and water content in this study. Crop water content data, in the form of the relative water content (RWC), were measured in the field for each type of crop. Crop water content was modelled based on the empirical relationships between spectral indices and field-measured RWC. The linear regression analysis revealed a significant association between the GNDVI and the water content of sweet potato, maize, sugar beans, and Florida broadleaf mustard, with r2 values of 0.948, 0.995, 0.978, and 0.953, respectively. The NDVI revealed a strong association with the water content of Solanum retroflexum, pepper, and cabbage, with r2 values of 0.949, 0.956, and 0.995, respectively. The NDRE, on the other hand, revealed a strong relationship with water content in peas and green beans, with r2 values of 0.961 and 0.974, respectively. The crop water content patterns simulation revealed that Solanum retroflexum, sweet potato, maize, sugar beans, and Florida broadleaf mustard reached their respective wilting points on day four after irrigation, implying that irrigation of these crops should be scheduled after every four (4) days. Peas, green beans, pepper, and cabbage reached their respective wilting points on day five after irrigation, implying that irrigation of these crops should be scheduled after every five days. The results of this study highlight the significance of considering crop water content derived from spectral bands of UAV imagery in scheduling irrigation for various types of crops. This study also emphasized the on-going significance of remote sensing technology in addressing agricultural issues that impede hunger alleviation and food security goals.

Modified QuEChERS method for phenolic compounds determination in mustard greens (Brassica juncea) using UHPLC-MS/MS

A modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, and Safe) for the determination of fifteen phenolic compounds in mustard greens (Brassica juncea) using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis was developed. The QuEChERS partitioning step and dispersive solid phase extraction (d-SPE) clean-up sorbents were investigated, aimed at phenolic compound extraction and pigment removal, respectively. QuEChERS acetate version combined with 25 mg of diatomaceous earth (DE) and 5.0 mg of graphitized carbon black (GCB) provided the best conditions for sample preparation of the target compounds. Under the optimized conditions, all phenolic compounds showed good linearity (r ≥ 0.99) over the concentration range of 0.1 to 8000 μg kg−1, and the quantification limits were in the range of 0.06–230 μg kg−1. The spectrophotometric analysis showed that the clean-up step promoted a significant removal of chlorophyll, which is the major pigment present in the sample. Furthermore, antioxidant activity analysis was also carried out after the clean-up step and, together with chromatographic data, showed that no significant retention of the phenolic compounds occurs in the clean-up step. Two mustard greens varieties – Southern Giant Curled (SGC) and Florida Broadleaf (FB) - were analyzed with the proposed method. Seven phenolic compounds (4-hydroxybenzoic, p-coumaric, ferulic and sinapic acids, naringenin, apigenin and kaempferol) were found in both varieties, the greatest abundance being for sinapic acid (1261.5 ± 23 μg kg−1 in SGC and 1235.5 ± 26 μg kg−1 in FB) and ferulic acid (2861 ± 24 μg kg−1 in SGC and 3204.5 ± 45 μg kg−1 in FB).

Suppression of Bacterial Blight on Mustard Greens with Host Plant Resistance and Acibenzolar-S-Methyl.

Bacterial blight, caused by Pseudomonas cannabina pv. alisalensis, attacks the leaves of most brassica vegetables, including mustard greens (Brassica juncea). 'Carolina Broadleaf,' a new mustard cultivar, is resistant to bacterial blight, whereas 'Florida Broadleaf,' a commonly grown cultivar, is susceptible. Acibenzolar-S-methyl (trade name Actigard) has been used to manage bacterial diseases caused by P. syringae on a variety of crops. The objective of this study was to evaluate host plant resistance and acibenzolar-S-methyl alone and in combination to manage bacterial blight. Three field experiments were done in spring and fall 2011 and fall 2014. In each experiment, acibenzolar-S-methyl was applied twice as a foliar spray, once before and once after plants were inoculated. Severity of bacterial blight was 81% less on nontreated Carolina Broadleaf than on nontreated Florida Broadleaf (P ≤ 0.0003). Acibenzolar-S-methyl applications reduced severity of bacterial blight by 55% compared with the water control treatment on susceptible Florida Broadleaf. Mean weight of diseased leaves, averaged across acibenzolar-S-methyl treatments, was 53% less with Carolina Broadleaf than with Florida Broadleaf (P < 0.0001). However, acibenzolar-S-methyl applied at the recommended rate (14.2 g/ha) significantly injured leaves of Carolina Broadleaf in two experiments and injured leaves of Florida Broadleaf in one experiment. Overall, host plant resistance was more effective than acibenzolar-S-methyl for managing bacterial blight on mustard greens.

Screening Brassicaceous Plants as Biofumigants for Management of Rhizoctonia solani AG1-IA.

Brassicaceae plants rich in glucosinolates have been used as biofumigants for management of Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) and other soilborne pathogens. Efficacy of brassica plant tissue has mainly been attributed to toxic isothiocyanates released upon hydrolysis of glucosinolates. Management of R. solani AG 1-IA, the causal agent of sheath blight in rice (Oryza sativa), using biofumigation, is promising but needs more validation. Biofumigation activity of nine Brassicaceae plants and two other related species were evaluated in vitro with soils from Texas, Arkansas, or Mississippi. All plants evaluated significantly suppressed the mycelium growth of R. solani AG 1-IA. Mustard (Brassica juncea) cultivars ('Brand 199', 'Ruby Streak', 'Florida Broadleaf', and 'Green Wave') consistently provided the greatest (>90%) mycelial inhibition, while sunn hemp (Crotalaria juncea) and Chinese cabbage (B. rapa) had the least suppressive effect. B. juncea 'Red Giant' and 'Sheali Hong', turnip (B. rapa), kale (B. oleracea), and arugula (Eruca sativa) showed intermediate efficacy or were inconsistent. Effects of soil pasteurization and plant tissue amendment rates were examined with B. juncea Brand 199 and Texas soil. Inhibition of mycelial growth became greater with increasing plant amendment rates up to 3.2% (wt/wt) in the soil. Soil pasteurization almost completely suppressed the release of allyl isothiocyanate (AITC). The nonpasteurized soil amended with 0.5% (wt/wt) of the plant material released 96% more AITC than the soil amended with 0.25% (wt/wt) of the plant material. The highest levels of AITC release were observed at 12 and 24 h after soil amendment, with 0.25 and 0.5% (wt/wt) of the plant material, respectively. Antifungal effects of B. juncea are attributed to dose-dependent production of volatile AITC and could be used for managing rice sheath blight caused by R. solani AG 1-IA.

First Report of Bacterial Leaf Blight on Mustard Greens (Brassica juncea) Caused by Pseudomonas cannabina pv. alisalensis in Mississippi.

In 2010, a brassica leafy greens grower in Sunflower County, MS, observed scattered outbreaks of a leaf blight on mustard greens (Brassica juncea) in a 180-ha field. A severe outbreak of leaf blight occurred on mustard greens and turnip greens (B. rapa) in the same field in 2011 with more than 80 ha affected. The affected field, established in 2010, had no prior history of being cropped to brassica leafy greens. Symptoms appeared on the 6-week-old transplants as brown to tan necrotic spots with faint chlorotic borders and associated water-soaking. Lesions varied from 4 mm to 3 cm in diameter and often coalesced to cover >90% of older leaves. Whole plants of the mustard greens cv. Florida Broadleaf were collected in 2011 from the symptomatic field. Leaves were surface-disinfested with 0.5% NaOCl for 5 min, rinsed twice in sterilized distilled water [(sd)H2O], macerated in sdH2O, then streaked onto nutrient agar (NA), pseudomonas agar F (PAF), and potato dextrose agar (PDA). Little or no bacterial growth was observed on PDA, while on NA and PAF the majority of bacterial growth appeared to be a single colony type. All strains collected (25 total, one per plant) were gram-negative and fluoresced blue-green under UV light after 48 h at 28°C on PAF. All 25 strains were identified as belonging to Pseudomonas group 1a using Lelliot's determinative assay (2). Ten of the 25 strains were tested for pathogenicity on Florida Broadleaf, and turnip greens cv. Alamo. Bacteria were grown on PAF for 48 h, and a bacterial suspension was prepared and adjusted to an optical density of 0.1 at 600 nm. Three-week-old plants (three plants per cultivar) were sprayed with the appropriate bacterial suspension to runoff, placed at 100% relative humidity for 48 h, and then put in a growth chamber at 28°C with a 16-h diurnal light cycle for 14 days. Additionally, three plants each of Florida Broadleaf and Alamo were either sprayed with H2O or inoculated with Pseudomonas cannabina pv. alisalensis (Pca) pathotype strain BS91 (1). All 10 strains, as well as the Pca pathotype strain, were pathogenic on both cultivars and caused symptoms similar to those observed in the field. Symptoms were not observed on H2O-sprayed plants. Comparative rep-PCR analysis using the BOXA1R primer showed the 10 strains had identical DNA-banding profiles and were identical to that of Pca BS91 (5). Five strains tested using a Pca-specific, 'light-tagged' reporter bacteriophage gave a strong positive reaction, while a negative control strain, P. syringae pv. maculicola, gave no signal (3). From these tests, the isolated bacteria were determined to be Pca. Bacteria re-isolated on PAF from the inoculated Florida Broadleaf plants had identical rep-PCR profiles with those of the strains used for inoculations. Over the past 10 years, Pca has been found in numerous states in the United States, as well as in Europe, Australia, and Japan (4). As brassica leafy greens production expands to new fields and new states, leaf blight caused by Pca appears to become a problem rapidly. Since resistant cultivars and highly effective bactericides are lacking, growers are extremely concerned about the rapid spread of this disease into existing and new brassica leafy greens regions.

Organic Leafy Greens Variety Trials in Kentucky: Identifying Superior Varieties for Small-scale Organic Farmers

Thirty-eight leafy greens, eight kale (Brassica oleracea acephala group), nine mustard (Brassica juncea), six arugula (Eruca sativa), five swiss chard (Beta vulgaris var. cicla), five collards (B. oleracea acephala group), and five turnip (Brassica rapa ssp. rapa) varieties were evaluated during Spring and Fall 2007–08 to determine suitability for organic production with respect to yield and stability. Trials were conducted on certified organic land using organic production practices. For mustard, kale, collards, and arugula, there were significant variety by season by year interactions. Despite these interactions, some varieties consistently performed well throughout the trial. ‘Florida Broadleaf’ was the highest yielding mustard in three of the four seasons evaluated. ‘Siberian’, ‘White Russian’, and ‘Red Russian’ were in the highest yielding group of kale varieties for overall yield. For collards, ‘Georgia/Southern’ and ‘Flash’ were part of the highest yielding group as determined by Duncan’s multiple range test in three of the four seasons examined. Turnip and swiss chard had significant year by variety interactions. Overall yields of ‘Alamo’ and ‘Alltop’, both F1 hybrids, were better than other turnip varieties assessed. Despite the interaction, ‘Fordhook Giant’ had superior yields in both years of the study. Arugula performance was significantly and negatively affected in Spring 2008. Overall, ‘Astro’, ‘Apollo’, and ‘Arugula’ had the greatest yields. This trial was designed to provide recommendations specifically for organic growers marketing directly to consumers.

Shoot tissue pigment levels increase in ‘Florida Broadleaf’ mustard (Brassica juncea L.) microgreens following high light treatment

The xanthophyll cycle pigments [zeaxanthin (ZEA)+antheraxanthin (ANT)+violaxanthin (VIO)] in plants are vital for energy dissipation of excess absorbed light. It is possible to manipulate xanthophyll cycle pigment levels through exposure to light. The objective of this study was to increase ZEA concentrations in mustard (Brassica juncea L. ‘Florida Broadleaf’) microgreens through exposure to high light just prior to tissue harvest. Mustard microgreen plants were cultured on growing pads in a controlled environment under a 14h photoperiod under 275μmolphotonsm−2s−1. Upon emergence of the first true leaf, light treatments of: (1) 275μmolphotonsm−2s−1; and (2) 463μmolphotonsm−2s−1 were initiated. Microgreen plants were harvested after light treatments had accumulated 36h during the photoperiod. Shoot pigments were measured for pigments using HPLC separation. Significant decreases in chlorophyll a (P≤0.001) and b (P≤0.01) concentrations under the 463μmolphotonsm−2s−1 light treatment indicated high light stress had occurred. There were significant decreases in β-carotene (P≤0.01) and neoxanthin (P≤0.001) in the 463μmolphotonsm−2s−1 light treatment; however, lutein concentrations were unchanged. Increases in ZEA (P≤0.001), and ANT (P≤0.01) occurred under the 463μmolphotonsm−2s−1 light treatment. Increasing the ZEA levels in microgreens with a simple change in light management may be an effective way for producers to enhance the nutritional value of this increasingly popular specialty crop.

Classification of temperature response in germination of Brassicas

Since soil temperature affects germination and emergence of Brassica napus L., mustard [ B. juncea (L.) Czerniak. and Sinapsis alba L.], and Camelina [ Camelina sativa (L.) Crantz.] planting dates have to be adjusted to prevent crop failures. These crops can be used as biofuel feedstocks and some mustard varieties can be used as a soil biofumigant. Knowledge of germination temperature optima/range for brassicas is critical for inclusion of these crops into crop rotations. The B. napus varieties ‘Clearwater’ (UI-C-1), ‘DKW 13-86’ (Roundup ® ready), and ‘Gem’ (UI-G-1); the mustards ‘Caliente 61’, ‘Florida Broadleaf’, ‘Idagold’, ‘Kodiak Brown’, and ‘Pacific Gold’, and the Camelina line ‘NEB C-1’ were germinated in the dark in Petri-dishes at 4, 10, 16, 21, 27 or 32 °C for up to 12 days. The shortest time to maximum germination (2 days) for all but ‘Florida Broadleaf’ and ‘Kodiak Brown’ occurred at 16 °C. ‘NEB C-1’ had the greatest percent germination at all temperatures except 32 °C where it was lower; ‘DKW 13-86’ decreased with increased temperature; ‘Clearwater’, ‘Gem’, ‘Pacific Gold’ and ‘Kodiak Brown’ had optimum germination between temperature extremes; ‘Caliente 61’ had the lowest maximum percent germination at 4 °C; ‘Florida Broadleaf’ had increased germination with increased temperature, and germination of ‘Idagold’ was not affected by temperature. Variability in Brassica seed germination in response to temperature indicates that there may be the opportunity for flexibility in the planting dates over which these crops can be sown.

Mercury‐induced oxidative stress in Indian mustard (Brassica juncea L.)

Mercury, a potent neurotoxin, is released to the environment in significant amounts by both natural processes and anthropogenic activities. No natural hyperaccumulator plant has been reported for mercury phytoremediation. Few studies have been conducted on the physiological responses of Indian mustard, a higher biomass plant with faster growth rates, to mercury pollution. This study investigated the phytotoxicity of mercury to Indian mustard (Brassica juncea L.) and mercury-induced oxidative stress in order to examine the potential application of Indian mustard to mercury phytoremediation. Two common cultivars (Florida Broadleaf and Longstanding) of Indian mustard were grown hydroponically in a mercury-spiked solution. Plant uptake, antioxidative enzymes, peroxides, and lipid peroxidation under mercury stress were investigated. Antioxidant enzymes (catalase, CAT; peroxidase, POD; and superoxide dismutase, SOD) were the most sensitive indices of mercury-induced oxidative response of Indian mustard plants. Indian mustard effectively generated an enzymatic antioxidant defense system (especially CAT) to scavenge H(2)O(2), resulting in lower H(2)O(2) in shoots with higher mercury concentrations. These two cultivars of Indian mustard demonstrated an efficient metabolic defense and adaptation system to mercury-induced oxidative stress. A majority of Hg was accumulated in the roots and low translocations of Hg from roots to shoots were found in two cultivars of Indian mustard. Thus Indian mustard might be a potential candidate plant for phytofiltration/phytostabilization of mercury contaminated waters and wastewater.

Phytotoxicity of mercury in Indian mustard ( Brassica juncea L.)

This study investigated the phytotoxicity of mercury to Indian mustard ( Brassica juncea L.). Two common cultivars (Florida Broad Leaf and Long-standing) were grown hydroponically in a mercury-spiked solution. Mercury exhibited a significant phytotoxicity in these two cultivars of Indian mustard at elevated concentrations (⩾2 mg L −1). Mercury uptake induced a significant reduction in both biomass and leaf relative water content. Microscopy studies indicated that elevated mercury concentrations in plants significantly changed leaf cellular structure: thickly stained areas surrounding the vascular bundles; decreases in the number of palisade and spongy parenchyma cells; and reduced cell size and clotted depositions. The palisade chloroplasts exhibited decreases in their amounts and starch grains as well as a loss of spindle shape. However, due to high accumulation of mercury in plants, especially in the roots, Indian mustard might be a potential candidate plant for phytofiltration of contaminated water and phytostabilization of mercury-contaminated soils.

First Report of Bacterial Leaf Spot on Leafy Brassica Greens Caused by Pseudomonas syringae pv. maculicola in South Carolina.

As of 2001, South Carolina ranked second in the United States in acreage of turnip greens (Brassica rapa) and collard (B. oleracea) and third in acreage of mustard (B. juncea). In June 2001, a leaf disease was found on turnip greens (cv. Alamo), mustard (cvs. Southern Giant Curled and Florida Broadleaf), and rape salad greens (B. napus var. napus cv. Essex) on a commercial farm in Lexington County, South Carolina. Symptoms appeared after a heavy rainstorm that included blowing sand. The disease was found in May and June 2002 on three additional farms in the same county on turnip greens cv. Topper and Royal Crown and collard cv. Top Bunch. Symptoms included small tan spots, water soaking, yellowing, and brown necrosis of leaves after spots coalesced on the lower halves of plants. Yellowing was more prevalent on older than on younger leaves. Leaf samples were collected in 2001 and 2002 from the affected hosts on the four farms. Bacterial streaming was evident from these samples and 27 strains were isolated on nutrient agar or King's medium B (KMB). All strains were gram negative and fluoresced bluegreen or yellow under UV light after 48-h growth at 28°C on Pseudomonas agar F (PAF). On the basis of LOPAT tests, the strains were identified as P. syringae (2). All 27 strains were tested for pathogenicity to rape salad greens cv. Essex and then to turnip greens cv. Topper. Plants were grown in peat-vermiculite potting mix in 10-cm-diameter pots in a greenhouse. P. syringae pv. maculicola F41, isolated from turnip in Oklahoma, and P. syringae pv. tomato F33, isolated from tomato in Oklahoma, were included as positive and negative controls along with a noninoculated control. Bacteria were grown on KMB for 48 h at 24°C, and bacterial suspensions were prepared and adjusted to 0.1 optical density at 600 nm. Three-week-old plants were held at 95 to 100% relative humidity (RH) for 48 h before they were sprayed just to runoff with inoculum and then held at 95 to 100% RH for 48 h after inoculation (4). After an additional 5 to 8 days in a greenhouse, nine strains and F41 caused symptoms on both Topper and Essex similar to symptoms observed in the field. No symptoms were observed on noninoculated plants or plants inoculated with F33. On the basis of repetitive sequence-based polymerase chain reactions with the BOXA1R primer, the DNA fingerprint of each of the nine pathogenic strains from South Carolina was nearly identical to that of F41. Bacteria isolated from inoculated, symptomatic turnip leaves had identical LOPAT and BOXA1R profiles to the corresponding original strains. Pathogenic strains had bluegreen fluorescence on PAF, whereas nonpathogenic strains fluoresced yellow. Five pathogenic strains, as well as F41, were further identified to species and pathovar with fatty acid methyl ester profiles as P. syringae pv. maculicola. To our knowledge, this is the first report of P. syringae pv. maculicola from South Carolina. Over the past 10 years, P. syringae pv. maculicola has been found in Oklahoma (4), California (1), and Ohio (3). Bacterial leaf spot has occurred yearly in South Carolina since the initial outbreaks. Currently, it is the disease that causes the greatest yield losses of leafy brassica greens in the state.

Preliminary Observations on the Effect of Light Intensity and Time of Day on Mustard Greens Leaf Ascorbic Acid and Greenness at Harvest

Field-grown mustard greens, Brassica juncea, were used to validate several observations of a greenhouse study which reported nutrient changes in mustard greens grown, in part, under ambient and reduced light. The cultivar Florida Broadleaf was transplanted into a Hildago sandy clay soil near Weslaco, Texas (26° 08' Lat.) on 6 Nov 2003. Greens were fertigated with 30 kg·ha-1 of N on 1 Dec. Plants 14 days before harvest were grown under the following four light regimes: (1) continuous ambient light; (2) 7 days of 50% shade then 7 days of ambient light; (3) 7 days of ambient light then 7 days of 50% shade; and (4) 14 days of 50% shade. Cumulative solar light was 28.9 and 19.4 kW/m2 during the first and second 7 days, respectively. Measured cumulative light, as PPFD, for treatments 1-4 were 108, 67, 78, and 44 mm·m-2·s-1, respectively. Plants were harvested at 0800, 1100, and 1400 h on 2 Jan. 2004. Shade during the last 7 days generally evoked the greatest responses. Increased shade duration did not significantly effect the agronomic performance, but did increase leaf total carotenoids, chlorophylls, water content, and reduced total ascorbate levels. As time of daylight progressed, sample plant weight and average leaf weight decreased in shaded plants only. Free ascorbic acid, chlorophyll a:b ratio, and the chlorophyll to carotenoid ratio decreased with time of day. Cumulative sunlight, as PPFD, was significantly correlated with total ascorbate (fresh weight basis), chlorophyll a:b ratio, and plant weight (P &lt; 0.06) and negatively correlated with chlorophylls and total carotenoids (dry weight basis). Thus, cloudy weather prior to harvest can reduce leaf Vitamin C and alter leaf greenness

Inhibition of Pythium ultimum and Rhizoctonia solani by Shredded Leaves of Brassica Species

The U.S. Clean Air Act bans the use of methyl bromide after 2005. Consequently, the development of alternative methods for control of soilborne pathogens is imperative. One alternative is to exploit the pesticidal properties of Brassica L. species. Macerated leaves (10 g) from `Premium Crop' broccoli [B. oleracea L. (Botrytis Group)], `Charmant' cabbage [B. oleracea L. (Capitata Group)], `Michihili Jade Pagoda' Chinese cabbage [B. rapa L. (Pekinensis Group)], `Blue Scotch Curled' kale [B. oleracea L. (Acephala Group)], Indian mustard [B. juncea (L.) Czerniak, unknown cultivar] or `Florida Broadleaf' mustard [B. juncea (L.) Czerniak] were placed in 500-mL glass jars. Petri dishes with either Pythium ultimum Trow or Rhizoctonia solani Kühn plugs on potato-dextrose agar were placed over the jar mouths. Radial growth of both fungi was suppressed most by Indian mustard. Volatiles were collected by solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry. Allyl isothiocyanate (AITC) comprised &gt;90% of the volatiles measured from `Florida Broadleaf' mustard and Indian mustard whereas (Z)-3-hexenyl acetate was the predominant compound emitted by the other species. Isothiocyanates were not detected by SPME from `Premium Crop' broccoli and `Blue Scotch Curled' kale although glucosinolates were found in freeze-dried leaves of all species. When exposed to AITC standard, P. ultimum growth was partially suppressed by 1.1 μmol·L-1 (μmol AITC/headspace volume) and completely suppressed by 2.2 μmol·L-1 R. solani was partially suppressed by 1.1, 2.2, and 3.3 μmol·L-1 AITC. Use of Brassica species for control of fungal pathogens is promising; the presence of AITC in both lines of B. juncea suppressed P. ultimum and R. solani but some Brassicas were inhibitory even when isothiocyanates were not detected.

Evaluating Leonardite as a Crop Growth Enhancer for Turnip and Mustard Greens

The objectives of this study were to determine if the use of leonardite as a fertilizer supplement improved crop growth and if there was a residual effect from previous applications. Three planting sequences were established and leonardite applied at 0, 50, 100, 200, and 400 lb/acre (0, 56.1, 112.1, 224.3 and 445.6 kg·ha−1). Subplots were treated at the first, the first and second, or all at three planting sequences. `Purple Top White Globe' turnip (Brassica rapa L.) and `Florida Broadleaf' mustard greens (Brassica hirta L.) were used as the indicator crops in the first two and last sequences, respectively. No differences in plant growth were observed among number of applications or treatment rate. Differences in soil potassium and iron were observed.

Inhibition of Fungal Growth by Macerated Plant Tissues in a Closed Environment

The U.S. Clean Air Act bans the use of methyl bromide after 2001. Consequently, the development of alternative methods for control of soilborne pathogens is imperative. One alternative is to exploit the pesticidal properties of macerated tissues of Brassica spp. This study tested the potential of several Brassica spp. for control of fungal pathogens. Pythium ultimum Trow or Rhizoctonia solani Kühn plugs on potato-dextrose agar on petri dishes were sealed in 500-ml glass jars (at 22 °C) containing macerated leaves (10 g) from one of six Brassica spp. Radial growth was measured 24, 48, and 72 h after inoculation. Indian mustard (B. juncea) was the most suppressive, followed by `Florida Broadleaf' mustard (B. juncea). Volatile compounds in the jars were sampled with a solid-phase microextraction device (SPME) and identified by gas chromatography-mass spectrometry (GC-MS). Allyl isothiocyanate (AITC) comprised over 90% of the total volatiles measured from Indian mustard and `Florida Broadleaf' mustard. Isothiocyanates were detected in jars with all plants except broccoli. (Z)-3-hexenyl acetate was emitted by all plants and was the predominant volatile of `Premium Crop' broccoli (B. oleracea L. var. italica), `Michihili Jade Pagoda' Chinese cabbage (B. pekinensis), `Charmant' cabbage (B. oleracea L. var. capitata), and `Blue Scotch Curled' kale (B. oleracea L. var. viridis). To assess the influence of AITC on radial growth of P. ultimum and R. solani, AITC was added to jars to give headspace concentrations of 0.10, 0.20, and 0.30 mg·L–1 (mass of AITC per volume of headspace). Growth of both fungi was inhibited by 0.10 mg·L–1 AITC. 0.20 mg·L–1 AITC was fungicidal to P. ultimum although the highest AITC level tested (0.30 mg·L–1) did not terminate R. solani growth. These results indicate that residues from some Brassica spp. may be a viable part of a soilborne pest control strategy.

Colorado Potato Beetle and Green Peach Aphid Control with Soil-Applied Insecticides and Foliar Sprays, 1997

Abstract Experimental plots were established on the UI Research and Extension Center, Kimberly, Idaho. Potatoes were planted on 28 Apr and irrigated by solid set sprinkler. The soil type was Portneuf silt loam. Ten treatments and one untreated check plot were replicated four times in a RCB design. Individual plots were 4 rows (36-inch row spacing) wide by 25 ft long with 5-ft alleyways separating the plots. Green peach aphids were mass reared in the greenhouse on mustard plants (Brassica juncea L. ‘Florida Broadleaf’) for release into individual plots. Aphid releases were made into test plots on 14 Jun. A total of four heavily infested leaves were released per plot. On a weekly basis, adults, large larvae (3-4 instar), small larvae (1-2 instar), and egg masses of Colorado potato beetle were counted and percent defoliation estimates were made from whole plant inspections of the center 5 hills of the middle 2 plot rows. Green peach aphid counts were made by non-destructively sampling 20 leaves at random from the top, middle, and bottom sections of plants in the center two rows of each plot. The data collected and presented is the total no. of aphids/20 leaves. Admire treatments were applied at planting as an in-furrow S over the seed piece on 28 Apr. Temik and Thimet were applied in-furrow with the seed piece at-planting. Post-emergence Admire was side dressed and shanked on 29 May. Furadan and the at-emergence, pre-hilling Admire treatment were applied on 6 Jun. Furadan was applied in a six-inch banded S over the plants at 4-inch rosette stage of plant growth using a CO2-pressurized backpack sprayer. The at-emergence, pre-hilling Admire treatment was shanked to the side of the plants (3 inch to side and 4 inch deep) and then hilled. On 26 Jun the CGA-215944 and Sevin treatments were S applied. All foliar S treatments were broadcast applied using the backpack CO2 sprayer at a rate of 20 gpa (30 psi, with 4, 10X hollow-cone nozzles). On 28 Jul a second foliar application of Furadan was made. Data were analyzed using ANOVA and Tukey’s HSD Test.

Green Peach Aphid Control with Foliar Sprays, 1997

Abstract Experimental plots were established on the UI Research and Extension Center, Kimberly, Idaho. Potatoes were planted on 28 Apr and irrigated by solid set sprinkler. The soil type was Portneuf silt loam. Seven treatments and one untreated check plot were replicated four times in a randomized complete block design. Individual treatment plots were 4 rows (36-inch row spacing) wide by 25 ft long with 5-ft alleyways separating the plots. Green peach aphids were mass reared on greenhouse mustard plants (Brassica juncea L. ‘Florida Broadleaf’) for release into individual plots. Aphid releases were made into test plots on 14 Jun. A total of four heavily infested leaves were used to inoculate each plot. Treatment sprays were broadcast applied using a CO2-pressurized backpack sprayer (30 psi) and delivering 20 gal finished S per acre (four, 10X hollow-cone nozzles). Aphid counts were made by non-destructively sampling leaves at random from the top, middle, and bottom sections of plants in the center two rows of each plot. The data collected and presented is the total no. of aphids per 20 leaves. On 25 Jun a pre-treatment count was made and all treatments were applied later that d. Data was analyzed using ANOVA and Newman-Keuls multiple means comparison (Significance Level P = 0.05).

Spool Versus Pan Bed Shapers for Vegetable Crops

Cabbage (Brassica oleracea L. Capitata ‘Fortuna’), mustard (Brassica juncea L. Czerniak ‘Florida Broadleaf’), Sweetcorn (Zea mays var. rugosa Bonaf. ‘SsuperSweet 7210Y’), southernpea (Vigna unguiculata [L.] Walp. ‘Pinkeye Purplehull’), and snapbean (Phaseolus vulgaris L. ‘Blue Lake 274’) were grown on precision-shaped raised beds formed with either a spool roller shaper or a pan shaper. Bed profiles were recorded at planting and again at harvest to determine changes in bed outline due to erosion and equipment operations. No differences in crop yield or final bed shape were noted. Either type of bed shaper can be effectively used in a precision cultural system; however, the spool shaper is easier to operate and does not drag soil to the ends of the field.

COVER CROP AND NITROGEN MANAGEMENT INFLUENCE YIELDS OF SEQUENTIALLY PLANTED VEGETABLES

A three year study was conducted in which fall-planted cover crops of hairy vetch, Austrian winter pea and crimson clover were each followed by spring-planted `Sundance' summer squash and `Dasher' cucumber. Squash and cucumber crops were followed by fall `Florida Broadleaf' mustard green and `Vates' collard, respectively. The same vegetable sequences were also planted without benefit of cover crop. Three nitrogen (N) rates were applied to each vegetable crop. Biomass and resulting N contribution of Austrian winter pea were inconsistent when compared to the other covers. Spring vegetables following crimson clover generally outyielded vegetables in the other sequences. Effects of cover on fall crops were greatest during the third year when vegetable yields following clover again exceeded yields from other sequences. Elimination of N fertilizer resulted in reduced yields for all crops, but yields of crops receiving one-half the recommended N rate were generally comparable to those receiving the full rate.

COVER CROP AND NITROGEN FERTILIZER RATE INFLUENCES ON YIELDS OF SEQUENTIALLY PLANTED VEGETABLES

Fall-planted cover crops of hairy vetch (Vicia villosa Roth), Austrian winter pea (Pisum sativum subsp. arvense L. Poir), and crimson clover (Trifolium incarnatum L.) were each followed by spring-planted 'Sundance' summer squash [Cucurbita pepo var. melopepo (L.) Alef.] and 'Dasher' cucumber (Cucumis sativus L.). Squash and cucumber crops were followed by fall 'Florida Broadleaf mustard green [Brassica juncea (L.) Czerniak] and 'Vates' collard (Brassica oleracea L. Acephala group), respectively. The same vegetable sequences were also planted without benefit of cover crop. Three nitrogen (N) rates were applied to each vegetable crop. Squash following winter pea and crimson clover produced greater yields than did squash planted without preceding cover crop. Cucumber following crimson clover produced the greatest yields. No cover crop effect was noted with mustard or collard. Elimination of N fertilizer resulted in reduced yields for all crops, but yields of crops with one-half the recommended N applied were generally comparable to those receiving the full recommended rate.