Search Results

You are looking at 31 - 40 of 60 items for

  • Author or Editor: Donald N. Maynard x
  • Refine by Access: All x
Clear All Modify Search
Open access

Donald N. Maynard

Abstract

Seedcoat adherence to emerged cotyledons of seedless watermelons (Citrullus lanatus (Thunb.) Matsum & Naki) results in distortion of seedlings that effectively restricts the number of productive plants in a planting. Significantly fewer seedcoats adhered to cotyledons when seeds were oriented with the radicle end up at a 45° or 90° angle than when seeds were oriented horizontally or with the radicle end down at a 45° or 90° angle. Emergence was not affected by seed orientation.

Open access

Donald N. Maynard

Abstract

Quality of horticultural crops is an extremely variable and perhaps nebulous characteristic. Quality may be easily expressed in physical terms such as size, color, or shape. Texture, food value, and keeping qualities, requiring more sophisticated determinations, are also critical components of quality. In some cases, quality may be a highly individual thing, varying from consumer to consumer. Furthermore, the expression of quality may be controlled by genetic capability as well as a host of environmental conditions.

Full access

Donald N. Maynard and Donald L. Hopkins

Watermelon (Citrullus lanatus [Thunb.] Matsum & Nakai) fruit are affected by a number of preharvest disorders that may limit their marketability and thereby restrict economic returns to growers. Pathogenic diseases discussed include bacterial rind necrosis (Erwinia sp.), bacterial fruit blotch [Acidovorax avenae subsp. citrulli (Schaad et al.) Willems et al.], anthracnose [Colletotrichum orbiculare (Berk & Mont.) Arx. syn. C. legenarium (Pass.) Ellis & Halst], gummy stem blight/black rot [Didymella bryoniae (Auersw.) Rehm], and phytophthora fruit rot (Phytophthora capsici Leonian). One insect-mediated disorder, rindworm damage is discussed. Physiological disorders considered are blossom-end rot, bottleneck, and sunburn. Additionally, cross stitch, greasy spot, and target cluster, disorders of unknown origin are discussed. Each defect is shown in color for easy identification.

Free access

Donald N. Maynard and Gary W. Elmstrom

Evaluations of 30 triploid (seedless) watermelon hybrids were conducted in the Spring 1989 season at Bradenton and Leesburg, Florida. There was considerable variation in relative cultivar yields at the two locations. However, consistency in some cultivars did occur. 'HMX 7924' produced the highest total yield and 'CFREC 88-2' had high total yields at both locations. On the other hand, 'ACX 882322', 'Fengshan No. 1', 'FMX 28', 'Fummy', 'Honeyheart', 'Nova', and 'NVH 4295' produced low total yields at both locations. Average fruit weight was high for 'Ssuper Sweet Brand 5244', 'CFREC 88-4', and 'HMX 7924' whereas 'ACX 882322', 'FMX 28', 'Fengshan No. 1', 'Nova', and 'PSR 49087' produced low average fruit weight. Soluble solids exceeded 11% in all entries at Bradenton whereas two entries were lower than 10% at Leesburg. Several experimental lines out performed the named cultivars suggesting that future introductions will be superior to those already available.

Free access

Gary W. Elmstrom and Donald N. Maynard

Muskmelon (Cucumis melo L. reticulatus group), commonly called cantaloupe by growers, shippers, and consumers is a relatively minor crop in the southeastern U.S. The principal restraint on increased muskmelon production in this area is the lack of varieties that consistently produce high quality fruit. Resistance to both fruit rots, especially those induced by Fusarium, and foliar diseases such as downy mildew, powdery mildew, and gummy stem blight are also important because of the high humidity and frequent rainfall common to this area. The ideal shipping variety should have the capacity to produce high yields of round to oval, sutureless, heavily netted fruit that average 1.4 kg each, and that have a deep salmon-colored flesh, a small tight seed cavity, high soluble solids, and a pleasant taste and aroma. Evaluations at Leesburg and Bradenton, Florida over a three-year period have identified several western-type muskmelons well-adapted to this area. `Explorer', `Goldmark', `Mission', and `Tasty Sweet' ranked high in most of the categories mentioned above and should be evaluated in more extensive trials, which should include a study of postharvest quality.

Free access

Jonathan R. Schultheis and Donald N. Maynard

Market demand for diploid fruit has been declining over the past ten years, especially the past three years. Thus, the watermelon industry is looking for ways to produce triploid fruit more efficiently. Several companies have developed pollinizers for planting in-row so as not to take up space like a commercial diploid cultivar. The objective of our experiment was to determine the effects of `Companion' and `SP-1' pollinizers on triploid yield compared with a traditional diploid pollinizer which until recently were routinely sold to grocery chain stores. The experimental locations were Bradenton, Florida and Kinston, NC. Treatments included two triploid cultivars; Tri-X-313 (Syngenta, Rogers Brand Seeds) and Olympia (Seminis Seed Co.), and three pollinizers; `Companion' (Seminis Seed Co.), `SP-1' (Syngenta, Rogers Brand Seeds), and `Summer Flavor 800' (Abbott & Cobb Seed Co.). A seventh treatment included `Tri × 313' in which no pollinizer was planted next to the triploid cultivar. `Companion' was interplanted every two triploid plants. `SP-1' was interplanted every three triploid plants, and `Summer Flavor 800' planted every third hill. All fruit were harvested when ripe and each watermelon was weighed. Results in the Florida location were compromised due to the close proximity of pollen from adjacent watermelon cultivar trials. In North Carolina, some pollen movement did occur between treatment plots as evidenced by fruit set in the `Tri-X-313' plots which did not contain a pollinizer. Yields; however, were 25% to 33% of those treatments which contained a pollinizer. `Tri × 313' yielded greater fruit numbers but individual fruit weights were less than those harvested from `Olympia'. Early fruit yield was similar regardless of pollinizer, while late yields were greater using `SP-1' rather than `Companion' or `Summer Flavor 800'. Cumulative yields (three total harvests) were highest with `SP-1' than the other pollinizers. The use of `SP-1' provided the greatest potential for improved yields over traditional diploid pollinizers.

Full access

William J. Lamont Jr

Knott's Handbook for Vegetable Growers, Fifth Edition. D.N. Maynard and G.J. Hochmuth. 2006. John Wiley and Sons, Inc., 111 River Street, Hoboken, NJ 07030. 640 pages. $75, paperback. ISBN: 978-0-471-73828-2.

The first Handbook for Vegetable Growers was published in 1956 by the late Dr. James Edward Knott, professor of vegetable crops, University of California, as an effort to “bring together in as concise a form as possible much of the widely scattered information that relates to vegetable production.” I have a copy of this

Full access

George J. Hochmuth and Donald N. Maynard

Delivery of modern extension programs involves considerable expenses that are becoming scarce from traditional sources. Successful extension educational programs will need to find additional revenue sources to fund educational materials, speaker costs, conferences, and other needs. It is important to become as financially efficient as possible and sometimes this means consolidating some programs and eliminating others. Charging fees to attendees is one means of covering costs of delivering programs. The University of Florida is partnering with the agriculture industry and trade journal publishers to provide resources and publishing for educational programs and materials.

Open access

Robert J. Precheur and Donald N. Maynard

Abstract

Transplants of asparagus (Asparagus officinalis L.) were grown in sand culture under varying ratios of NO3 and NH4. Maximum growth occurred in a nutrient solution with a N ratio of 75% NO3 – N and 25% NH4 – N. Growth was significantly reduced when the N composition was either 100 or 75% NH4 – N. CaCO3 reduced ammonium toxicity but also reduced seedling growth.

Open access

Donald N. Maynard and Allen V. Barker

Abstract

Spinach, Spinacia oleracea, L., cv. America, Heavy Pack, and Hybrid 424 were grown in sand culture with variable NO3 concentrations from 0.187 to 48 meq/l. The cultivars were representative of savoyed, semisavoyed, and smooth-leaf types, respectively. The plants were harvested when those cultured at 12 and 18 meq NO3/l had obtained approximate market maturity. At this time an array of deficiency, sufficiency, and toxicity symptoms were evident. Great differences in NO3 accumulation and critical NO3 concentrations occurred among cultivars. Critical NO3-N concentrations for the whole leaves of spinach plants were: ‘America’, 0.17%, ‘Heavy Pack’, 0.15%, and ‘Hybrid 424’, 0.045% of their dry weights. Calculations relating spinach consumption and impaired human health suggest that adult health should not be affected even with massive ingestion of spinach.