Search Results
You are looking at 11 - 20 of 34 items for
- Author or Editor: John Masiunas x
We compared soil quality, crop growth, and the incidence of pests in snapbean (Phaseolus vulgaris L.) planted in conventional tillage, in rye (Secale cereale L.) mulch without strips and in strip-tilled rye mulch. On average, yield loss was 63% in rye mulch without strips and 20% in rye mulch with strips compared to yields in conventional tillage. Soil bulk density was higher in the rye mulch treatments than in the conventionally tilled plots and may have reduced plant growth. Leaf nitrogen content was lower in the rye mulch treatments 3 weeks after planting; this may be related to nitrogen tie-up during rye decomposition or to the negative impact of soil compaction on the soil nitrogen cycle. Insect damage to snapbean pods and leaves was not affected by rye mulching. Potato leafhopper [Empoasca fabae (Harris)] populations were significantly higher for conventional tillage than for rye treatments. The incidence of white mold [Sclerotina sclerotiorum (Lib.) deBary] was reduced by the rye treatments in 1997. Further studies are needed to determine optimal strip width and develop better techniques for creating strips.
In the past few years, leaf trichomes of tomato (Lycopersicon esculentum) and related wild species have received considerable attention due to their potential role in insect resistance. However, the last complete characterization of all 7 trichome types was by Luckwill in 1943, before the advent of scanning electron microscopy (SEM). Since that time, the taxonomic designations of the genus have been modified, expanding from 6 species to 9. The purpose of this work was to use SEM to observe and record trichome types from the presently accepted Lycopersicon species, and determin etheir species specific distribution. Studies have shown variation within trichome type due to number of cells per trichome, and base and surface characteristics.
Studies established the critical period for eastern black nightshade (nightshade) (Solanum ptycanthum Dun.) competition in pea (Pisum sativum L.) and determined the effect of N fertility on pea and nightshade growth. In 1992, pea yields were most affected when nightshade was established at planting and remained for 4 or 6 weeks, while in 1993, competition for 6 weeks caused the greatest reduction in pea yields. In a sand culture study, pea biomass and N content were not affected by three N levels (2.1, 21, and 210 mg·L-1). Nightshade plants were five to six times larger in the highest N treatment than at lower N levels. Nitrogen content of nightshade was 0.76% at 2.1 ppm N and 3.22% at 210 ppm N. Choosing soils with low N levels or reducing the N rates used in pea may decrease nightshade interference and berry contamination of pea.
A three-year study determined the effect of winter cover crops on weeds and vegetable crops in a vegetable production system. Winter rye and hairy vetch were interseeded in the fall of 1990, 1991 and 1992 at 112 and 34-kg ha-1, respectively. The cover crops were killed by ether applying glyphosate at 1.1 kg a.i ha-1 [reduced tillage(RT)] or mowing and disking the cover crop (Disked). The conventional tillage (CT) was bare ground with a preplant incorporated application of 0.84 kg a.i ha-1 of trifluralin. During the three years, the greatest snap bean yields were in the CT; total yields of cabbage and tomato varied between the years; and were not affected by management systems. Weed control was similar in the RT and CT treatments during the three years. Disked cover crop treatments tended to have greater weed numbers than either RT or CT treatments.
Fresh-market vegetable production in the midwestern U.S. has been declining due to diminished returns received by farmers, competition from vegetables produced in other regions, older farmers retiring and not being replaced, and urban sprawl. To reverse this trend, midwestern-U.S. vegetable farmers must find ways to enhance the value of their production. One way might be the production of vegetable cultivars that have enhanced attributes desired by consumers. Our objective was to assess how Illinois farmers' current perceptions may affect acceptance and production of vegetable cultivars with enhanced health benefits. About 20% of Illinois fresh-market vegetable growers were surveyed. We found that the current media attention on genetically modified organisms (GMOs) infl uenced grower response. Farmers who were concerned about GMOs were 5 times more likely to reject growing new vegetable cultivars with enhanced health benefits even those developed with conventional breeding methods. However, farmers who were not concerned or who were undecided in their opinions concerning GMOs were 11 times more likely to adopt new cultivars. Education and research programs must be developed to supply information about vegetable cultivars with enhanced health benefits and to address farmers' concerns about GMOs.
Winter-killed cover crops may protect the soil surface from erosion and reduce herbicide use in an early planted crop such as pea (Pisum sativum). Our objective was to determine the potential of winter-killed cover crops in a snap pea production system. White mustard (Brassica hirta) produced the most residue in the fall but retained only 37% of that residue into the spring. Barley (Hordeum vulgare) and oats (Avena sativa) produced less fall residue but had more residue and ground cover in the spring. Greater ground cover in the spring facilitated higher soil moisture, contributing to higher weed numbers and weight and lower pea yields for oat and barley compared with a bare ground treatment. White mustard had weed populations and pea yields similar to the bare ground treatment. Within the weed-free subplot, no differences in pea yields existed among cover crop treatments, indicating no direct interference with pea growth by the residues. In greenhouse experiments, field-grown oat and barley residue suppressed greater than 50% of the germination of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursapastoris), while in the field none of the cover crop provided better weed control than the fallow.
Greenhouse hydroponics and field experiments were conducted to determine how nitrogen (N) fertilizer treatments affect tomato (Lycopersicon esculentum Mill.) growth, yield, and partitioning of N in an effort to develop more sustainable fertilization strategies. In a hydroponics study, after 4 weeks in nitrate treatments, shoot dry weight was five times greater at 10.0 than at 0.2 mm nitrate. An exponential growth model was strongly correlated with tomato root growth at all but 0.2 mm nitrate and shoot growth in 10 mm nitrate. Root dry weight was only 15% of shoot biomass. In field studies with different population densities and N rates, height in the 4.2 plants/m2 was similar, but shoot weight was less than in the 3.2 plants/m2. At 12 weeks after planting, shoot fresh weight averaged 3.59 and 2.67 kg/plant in treatments with 3.2 and 4.2 plants/m2, respectively. In 1998, final tomato yield did not respond to N rate. In 1999, there was a substantial increase in fruit yield when plants were fertilized with 168 kg·ha-1 N but little change in yield with additional N. Nitrogen content of the leaves and the portion of N from applied fertilizer decreased as the plants grew, and as N was remobilized for fruit production. Both studies indicate that decreasing N as a way to reduce N loss to the environment would also reduce tomato growth.
Black polyethylene mulch and weed control strategies were evaluated for potential use by small acreage herb producers. In both 1988 and 1989, the mulch greatly increased fresh and dry weight yields of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.). Parsley (Petroselinum crispum Nym.) yield did not respond to the mulch. Preplant application of napropamide provided weed control for 2 weeks, but was subsequently not effective on a heavy infestation of purslane (Portulaca oleracea L.). Hand-hoed and glyphosate-treated plots (both with and without plastic) produced equivalent yields. Chemical names used: N, N -diethyl-2(1-napthalenoxy)-propanamide (napropamide); N- (phosphonomethyl) glycine (glyphosate).
Winter-killed oats (Avena sativa) may have potential for use to suppress weeds in early seeded crops such as pea (Pisum sativum). Residue biomass and surface coverage are generally correlated with weed suppression. Oat residues also contain allelochemicals. Our objective was to determine if oat cultivars vary in residue production and allelopathy. Differences between oat cultivars were observed in residue production, and for effects on emergence of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursa-pastoris) in the greenhouse, and germination of pea and common lambsquarters in an infusion assay. Two of the oat cultivars producing the greatest biomass, `Blaze' (in the field) and `Classic' (in the greenhouse), interfered minimally with pea germination and were among the best cultivars in inhibiting common lambsquarters and shepherd's-purse. `Blaze' also greatly inhibited common lambsquarters germination in the infusion assay that measured allelopathy. Thus, `Blaze' and `Classic' possess suitable characteristics for use as a cover crop preceding peas.
Our previous research found that snap bean yields were reduced in cropping systems with cereal rye residues. Strip-tillage may overcome the yield reductions while providing the environmental advantages of high residue systems. An experiment was established at Champaign, Ill. `Wheeler' cereal rye was seeded in September at 110 kg·ha–1. The treatments were 1) conventional tillage with trifluralin, 2) rye without strips, 3) rye with fall-established strips, and 4) rye with spring-established strips. The rye was mowed 1 week before planting the snap beans. The spring strips were established in solid-seeded rye using a no-till planter, modified with extra culvers. It was difficult to maintain the fall-established strips after mowing. Weed control in the strips was problematic. Yields and insect populations were also determined.