A Study of Some Herbicides Applied Pre-emergence and the Influence of Rainfall Upon their Activity

Weeds have been with man for countless years and it is evident that they will be with man for many more. As tillable land decreases and population increases, weeds will have to be controlled to insure the best land use. Weeds are controlled by cultural, biological and chemical methods. Cultural practices are most widely used and generally the most practical. Biological control is useful only in specific areas. Chemical control of weeds was not widely used method until the discovery of selective herbicides about 1900. A group of chemicals now receiving much attention are the herbicides commonly called “pre-emergence chemicals.” These chemicals are so named because of their time of application. The possibility of controlling annual weeds by pre-emergence applications of herbicides on large acreages of corn without the aid of cultivation has stimulated a large amount of interest. The objective of this study was to learn more about a relatively new group of herbicides used primarily as pre-emergence treatments in corn and how the control of annual weeds is influenced by the time and amount of rainfall that is received after the chemical is applied. These new chemicals are simazine and atrazine

Growth and Yield Potential of Green Pepper as Affected by Nitrogen at Transplanting

Green pepper (Capsicum annuum L. cv. Lady Bell) was grown for 7 weeks and transplanted into the field. The following rates of N were applied: 112, 224, 336 and 448 kg/ha. High N rates at transplanting did not stimulate vegetative growth but suppressed plant growth, particularly during the early growing period. As N rates increased, plants exhibited poor early growth and produced lower early and total fruit yields. Early yield positively correlated with plant dry weight. Doubling the N rate from 112 to 224 kg/ha resulted in a 21% increase in flower buds, but the percentage of fruit set decreased as N rates increased. Fruit set correlated negatively with total leaf N and positively with plant weight, suggesting that a high leaf N content and a lower plant weight were detrimental to fruit set and yield of green pepper

The distribution of carbon and the demand of the fungal symbiont in leek plants with vesicular arbuscular mycorrhizas

RESP-893

Ascomycetous yeast species recovered from grapes damaged by honeydew and sour rot

Aims: To identify ascomycetous yeasts recovered from sound and damaged grapes by the presence of honeydew or sour rot. Methods and Results: In sound grapes, the mean yeast counts ranged from 3.20 ± 1.04 log CFU g-1 to 5.87 ± 0.64 log CFU g-1. In honeydew grapes, the mean counts ranged from 3.88 ± 0.80 log CFU g-1 to 6.64 ± 0.77 log CFU g-1. In sour rot grapes counts varied between 6.34 ± 1.03 and 7.68 ± 0.38 log CFU g-1. Hanseniaspora uvarum was the most frequent species from sound samples. In both types of damage, the most frequent species were Candida vanderwaltii, H. uvarum and Zygoascus hellenicus. The latter species was recovered in high frequency because of the utilization of the selective medium DBDM (Dekkera ⁄ Brettanomyces differential medium). The scarce isolation frequency of the wine spoilage species Zygosaccharomyces bailii (in sour rotten grapes) and Zygosaccharomyces bisporus (in honeydew affected grapes) could only be demonstrated by the use of the selective medium ZDM (Zygosaccharomyces differential medium). Conclusions: The isolation of several species only from damaged grapes indicates that damage constituted the main factor determining yeast diversity. The utilization of selective media is required for eliciting the recovery of potentially wine spoilage species. Significance and Impact of the Study: The impact of damaged grapes in the yeast ecology of grapes has been underestimate