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Fine fescues are immune to two common graminicides, fluazifop-p-butyl and sethoxydim. This study was initiated to determine the tolerance of three fine fescues; chewings, hard, and creeping red, to clethodim alone or with a crop oil concentrate (COC) or non-ionic surfactant (NIS). Clethodim at 0.25 or 1.0 lb/a was applied on 23 Oct. 1995 and evaluated on 22 May and 9 July 1996. Clethodim at 0.25, 0.5, or 1.0 lb/a, was applied on 31 May and evaluated on 9 July 1996. Applied in the fall at 0.25 lb/a alone or with NIS, clethodim had little effect on chewings or creeping red fescue. Some injury to hard fescue was evident on 22 May, but it recovered by 9 July. The addition of COC resulted in moderate injury to all three species, with only partial recovery by 9 July. Severe injury of all species from clethodim applied at 1 lb/a was evident on 22 May. The amount of recovery that occurred by 9 July was dependent on the spray additive used. With none, all of the grasses recovered fairly well. With NIS, moderate injury to hard fescue persisted; and with COC, unacceptable injury to all species persisted. Similar results were obtained when the treatments were applied in the spring. The 0.5 lb/a rate caused an intermediate degree of injury. Though none of the clethodim treatments totally killed any of the fine fescues, unacceptable injury was caused by the 0.5 and 1.0 lb/a rates, regardless of additive, and by the 0.25 lb/a + COC treatment.
A study was initiated to determine how well plants would grow in potting media available to consumers through garden centers and national chain stores. Nine media were evaluated. The chemical and physical characteristics were determined, and six geraniums (Pelargonium sp) and six marigolds (Tagetes patula) were grown in each of the media. Three of each six were fertilized, three were not. The plants that were fertilized received 100 ppm N and K and 50 ppm P once a week. Three months after seeding the flowers, flowers and buds on the marigolds were counted and the plants were harvested. Dry weights were determined. Nitrate-N ranged from 6 to 627 ppm, pH from 4.9 to 7.1, phosphorus from 88 to 502 pounds/A, potassium from 1.0 to 6.9 meq/100 g, magnesium from 1.4 to 10.8 meq/100 g, calcium from 5.2 to 30.0 meq/100 g, soluble salts from 20 to 151 mmhos, and CEC from 13.0 to 43.8 meq/100cc. Bulk density ranged from 21 to 53 g/100cc, water holding capacity from 32 to 53 ml/100cc, percent air-pore space from 2.7 to 15.7, and total porosity ranged from 65% to 78%. Unfertilized marigolds weighed between 0.1 and 9.6 g; fertilized marigolds weighed 1.4 to 17.2 g. Unfertilized geraniums weighed between 1.4 and 23.3 g; fertilized geraniums weighed 4.4 to 56 g. There were 1.3 to 16 flowers on unfertilized and 7 to 24.3 flowers on fertilized marigolds.
Weeds must be controlled to produce marketable crop yields, for human safety, and for aesthetic reasons. Physical methods of weed control are highly labor and/or energy intensive, and in many cases are more dangerous to crops and people than herbicides. They are not practical solutions to most weed problems in developed countries. To properly work with and apply herbicides, researchers, and applicators should have a knowledge base that includes information on weed taxonomy, anatomy, and biology; herbicide chemistry and modes of action; spray adjuvants and carriers; soil characteristics and environmental factors that affect herbicide performance; application equipment technology; the development of herbicide resistance; alleleopathy; and the biological control of weeds. Herbicide use, in terms of product used or expenditures, is greater by a wide margin than that of insecticides and fungicides combined. Also, about two thirds of all pesticides produced in, and exported from, the United States are herbicides. Finally, about 40% of all of the herbicides used in the world are used in the United States. Only 32% of the insecticides and 14% of the fungicides are used in the United States. On the average, the leading universities in the country have only three faculty teaching courses in weed science, and they teach only two undergraduate and three graduate courses each year. Few are in horticulture. By comparison, there are 15 faculty teaching 13 undergraduate and 19 graduate courses in the leading entomology programs in the country. Weed control is an essential element in the production and management of all horticultural crops. Who is going to provide the education and training in weed science for the researchers, horticulturists, and consultants of the future?
In 1995, Monsanto Chemical Co. announced that they would replace Roundup herbicide with Roundup Pro for use in the ornamentals and turf markets. Both products contain 4 lb a.i./gal glyphosate, but Roundup Pro contains a more-active surfactant. Though Roundup was labeled as a nonselective herbicide, dormant conifers were found to have varying degrees of resistance to it. Directed sprays that hit the lower two-thirds of many dormant conifers became common practice in the industry. Because the surfactant in Roundup Pro increases the activity of the glyphosate, a series of trials were initiated in 1996 in Connecticut, Pennsylvania, and Vermont in which four glyphosate formulations were applied to a variety of dormant conifers. Roundup, Roundup Pro, Glyfos, and Accord (with and without surfactant) were applied either over-the-top or as directed sprays to the lower 18 inches of the plants at rates between 0.5 and 3 lb a.i./acre. Plants treated included globe arborvitae; upright yew; Canadian hemlock; Colorado, Norway and white spruce; Douglas fir; eastern white pine; and balsam, Canaan, and Fraser fir. In a preliminary study, injury to the spruces in the form of dwarfed and chlorotic new growth was primarily associated with fresh pruning wounds. Accord plus surfactant and Roundup Pro injured more spruces than Roundup, but injury was slight. No injury was observed in upright yew with any formulation at rates up to 0.75 lb a.i./acre. Injury to arborvitae was greatest with Accord plus surfactant, intermediate with Roundup Pro, and least with Roundup. Results are inconclusive at this time, but the results of additional studies available early in the next growing season.will be presented.
A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.
Abstract
Extracts from freshly harvested tubers of potato (Solanum tuberosum L.) held at different temperatures and extracts taken from stored tubers were examined by starch gel electrophoresis. Storage of tubers at 10°C for up to 70 days or storage of extracts at −60° for 70 days did not affect isozyme banding patterns. Storage of fresh extracts for 14 days at 5° produced blurring of alkaline phosphatase (AKP) bands, altered isozyme mobility of malic enzyme, and added a band to glucosephosphateisomerase (GPI) zymograms. It did not affect the mobility or resolution of 6-phosphogluconate dehydrogenase. Addition of 0.1 m mercaptoethanol did not restore original resolutions or mobilities.
Avocado (Persea americana Mill.) has an unusual flowering mechanism, diurnally synchronous protogynous dichogamy, that promotes crosspollination among avocado genotypes. In commercial groves, which usually contain pollinizer rows adjacent to the more desirable commercial cultivars, the rate of outcrossing has been measured with variable results. Using microsatellite markers, we estimated outcrossing in a commercial California ‘Hass’ avocado orchard with adjacent ‘Bacon’ pollinizers. Seedlings grown from mature harvested fruit of both cultivars were genotyped with five fully informative microsatellite markers and their parentage determined. Among the 919 seedlings of ‘Hass’, 688 (75%) were hybrids with ‘Bacon’; the remaining 231 (25%) seedlings were selfs of ‘Hass’. Among the 850 seedlings of ‘Bacon’, 382 (45%) were hybrids with ‘Hass’ and the remaining 468 (55%) seedlings were selfs of ‘Bacon’. The high outcrossing rate observed in the ‘Hass’ seedlings was expected, because adjacent rows of opposite flowering types (A versus B) are expected to outcross. However, the high selfing rate in ‘Bacon’ was unexpected. A previous study in Florida using the cultivars ‘Simmonds’ and ‘Tonnage’ demonstrated differences in outcrossing rates between complementary flowering type cultivars. In both Florida and California, the A type parents (‘Hass’ and ‘Simmonds’) had similar outcrossing rates (≈75%); however, the B type parents (‘Bacon’ and ‘Tonnage”) had highly skewed outcrossing rates of 45% and 96%, respectively. Two new avocado lethal mutants were discovered among the selfed seedlings of ‘Hass’ and ‘Bacon’. These were labeled “spindly” and “gnarly” and are similar in phenotype to mutants described in Arabidopsis and other crop species.
The ability to rapidly genotype a large number of individuals is the key to any successful marker-assisted plant breeding program. One of the primary bottlenecks in high-throughput screening is the preparation of DNA samples, particularly the quantification and normalization of samples for downstream processing. A rapid and simple Sybr Green I-based quantification procedure that can be performed in a 96-well format is outlined. In this procedure, a dual standard curve method is used to allow better resolution of dilute samples and to reduce fluorescence value variation between samplings. A method to quickly normalize samples, and the importance of normalization, is also explored. We demonstrate that successful fragment amplification of a Theobroma grandiflorum (Willd ex Spreng) Schum. population is increased from 70% to 98% when each DNA extract is quantified and normalized as opposed to quantifying only a subset and normalizing all the samples based on the average of that subset. Improved microsatellite amplification was also observed among individuals in the monocot genus Phaedranassa Herb. ssp. Additionally, when our normalization method is applied to a Persea americana Mill. population, 97% of the samples normalized to 4 ng·μL−1 amplify at least three of six microsatellite regions, whereas only 30% of the samples below 4 ng·μL−1 (i.e., samples that could not be normalized) amplify at least three regions. We describe an undemanding method to quantify and normalize a large number of samples, which can be done manually or can be automated.