Biodegradable mulches made from kraft paper coated with polymerized (cured) vegetable oils were compared to black polyethylene mulches for promoting the growth of watermelon in northern Florida. Data from three spring growing seasons have been collected. Yields of watermelon planted on paper-soy oil and paper-linseed oil mulches were similar to those obtained for the control polyethylene mulches. This was the case where the paper-oil was cured before field application as well as when the paper-oil was applied to the field wet and curing took place in situ. Paper-oil mulches containing carbon black effectively blocked nutsedge growth, while nutsedge pierced and grew through the black polyethylene mulch. Degradation of the buried tucks were more rapid initially for paper-soy oil than paper-linseed oil mulch, but both lasted long enough to hold the mulch in place until spring harvests (≈2.5 months). In conclusion, paper coated with polymerized vegetable oil appears to be an effective substitute for polyethylene mulch for growing watermelon in Florida, although drawbacks include messiness in handling oily paper, slower application speeds, higher initial costs than polyethylene, and variability in rates of curing and degradation depending on soil and weather conditions.
butcher paper, 50-lb brown kraft paper, 30-lb brown waxed paper, and 50-lb kraft paper coated with a 10-lb polyethylene film facing the ground (Uline, Chicago). All mulches were obtained as 36-inch-wide rolls and were set on flat beds in the field using a
Plant breeders must be aware of sources of resistance to pathogens that affect their crops. Fusarium wilt caused by Fusarium oxysporum Schl. f. sp. pisi Snyd. & Hans. is a fungal disease that affects peas and is important worldwide. Resistance to the different races of the pathogen has been identified in adapted germplasm and from specific accessions in the United States World Collection of peas (Pisum sativum L.). The goal of this study was to evaluate the resistance to fusarium wilt race 2 in the Pisum core collection. Of the 452 accessions screened, 62 (14%) were resistant. The resistant accessions included accessions from P.s. ssp. elatius that were collected from 24 different countries. The wide distribution of resistance around the world precludes the identification of any single country or region as a source of resistance. Of the 62 accessions resistant to race 2, 39 are also resistant to race 1 based on data obtained from GRIN. One of the wild progenitors, PI 344012, possessed resistance to races 1 and 2.
assistance in testing: E. Gritton, Wisconsin Agricultural Experiment Station; J. Kraft, U.S. Dept. of Agriculture/Agricultural Research Service; and R. McGee, The Pillsbury Co. The cost of publishing this paper was defrayed in part by the payment of page
Producers' Marketing Board, Kraft Canada Inc., the Food Science Biotechnology Centre of the University of Guelph, and the National Science and Engineering Research Council. The assistance of Agriculture and Agri-Food Canada, in providing plants as well as
In 1994, field trials were undertaken to evaluate the agronomic performance of a range of paper mulches in vegetable production. During the course of the experiments, the majority of the paper mulches tested degraded part way through the growing season. Before the next growing season, a range of Kraft papers differing in densities and compositions were subjected to an accelerated degradation test to determine which mulches would be suitable for use under Quebec field conditions. A mixture of equal parts black soil, sand, and manure (two parts sheep manure and one part liquid cow manure) was placed into trays of 26 x 52 cm. Experimental papers were cut into strips measuring 2.5 x l.5 cm and put into the trays such that half of the strips were covered with the mixture. The trays were placed in a growth cabinet (30C with a relative humidity of 50%). Three replicates of each treatment were sampled 3, 5, 7, 11, and 14 days after placement to determined the amount of degradation that had taken place. It was found that the length of time taken for degradation in the accelerated system was 3.7 times less than that of the field.
Mineralization of N from nonviable cells of Brevibacterium lactofermentum (Okumura et al.) mixed into soilless substrate in elution columns occurred largely during the first 5 weeks with a peak between 2 and 3 weeks. Over a 12-week period, 73% of the total N was recovered in the eluent. To prolong the period of N release to meet the requirements of a slow-release fertilizer, the bacterium was bonded to kraft lignin, a polyphenolic substance highly resistant to degradation. To retard mineralization further, the bacterium-lignin mixture was reacted with formaldehyde to form amino cross-links within and between protein chains. Bonding to lignin was undesirable because N release occurred during the same period as from the bacteria unbound to lignin and the total amount of N recovered was reduced to only 42%. Cross-linking with formaldehyde was less desirable since N was released mainly during the first 4 weeks with a peak during the first elution (0 time) and the total amount of N released was even lower than for the bacterium-lignin mixture. Additions of urea to the latter reaction did not satisfactorily improve subsequent N mineralization. In a second set of treatments lignin was withheld and the bacterium was reacted with weights of formaldehyde (a.i.) equivalent to 0.1%, 0.5%, 1.0%, 5.0%, and 10.0% of the dry weight of bacterium. Formaldehyde quantities ≤1.0% either had no effect or lowered the mineralization of N without altering time of release. Five percent and 10% formaldehyde successfully reduced release of N during the first 4 weeks and increased it thereafter. The best rate was 5%. In this treatment N was released from week 2 through the end of the test (12 weeks). Peak release occurred at 6 weeks. This resulting N source, while not a stand alone product, does have a slow-release property that could lend itself to use in combination with other slow-release N sources.
Adequate weed control in the establishment year of matted-row strawberries (Fragaria × ananassa) is crucial for the long-term viability of plantings. Suppression of weed growth until the new strawberry plants are established and runners rooted is an effective strategy in new plantings. Three biodegradable mulch films were compared to standard weed control for establishing matted-row strawberries. Two films were test products using a biodegradable polymer, either clear or black, covering brown 40-lb kraft paper (IP40 Clear and IP40 Black, respectively). The third material was Planters paper, a black paper mulch. The films were evaluated for weed suppression, rate of degradation and effects on runner production and fruit yield. Additionally, the ability of runners that were formed to root as the film degraded was also observed. The IP40 Black mulch reduced the number of weeds compared to the standard control but did not degrade quickly enough for runners to root. The Planters paper also had fewer weeds, but it degraded quickly along the edges where it was covered by soil. This allowed the wind to tear it and blow large pieces off the plots. The IP40 Clear degraded in a timely manner and allowed runner rooting, but it was not acceptable as a weed suppression material. The IP40 Black and Planters paper mulches were effective for weed control in the establishment year, but rate of degradation was too slow in the former case and too fast in the latter. Runner production and fruit yield were not affected by any of the mulch materials compared to standard control.
seed germination of this cultivar). Seeds were stored in small Kraft envelopes in a threshing shed for 6 months. Seeds were then planted in steam-sterilized soil and allowed to germinate for 45 d. During the germination period, the seeds were subjected
formulations helps to prevent breakdown, inactivation, and loss of effectiveness of active ingredients ( Scher, 1999 ). Kraft lignin, the alkali-soluble/acid-insoluble polyphenolic polymer produced as a coproduct in the kraft wood-pulping process, is also used