Open Field Crops Research Articles

Biological and serological characterization of viruses of summer squash crops in Yugoslavia

A survey on summer squash open field crops was carried out during 2000 and 2001 in order to identify the major viruses infecting these crops in different localities. Plants showed different types of symptoms: mild mosaic, chlorotic spotting, distinctive mosaic, blistering of leaf lamina leaf yellowing, deformation of leaf lamina, knobbed fruits and stunting of plants. The symptoms were very variable but showed the viral nature of the investigated summer squash diseases. The collected samples were tested by bioassay and by two serological methods ELISA and EBIA using cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 2 (WMV-2), zucchini yellow flack potyvirus (ZYFV) watermelon mosaic potyvirus 1 (WMV-1), squash mosaic comovirus (SqMV) and cucurbit aphid-borne yellows polerovirus (CABYV) polyclonal antisera. In all tested samples single or mixed infection with ZYMV, CMV and WMV-2 was detected. The most prevalent virus infecting summer squash was ZYMV. This is the first report of ZYMV, the most destructive virus infecting cucurbits, in Yugoslavia. It was also proven that the identified viruses are transmissible by Aphis gossypii in a non-persistent manner, but possible role of seed in virus transmission was not confirmed.

Integrating soil solarization with grafting on resistant rootstocks for management of soil-borne pathogens of eggplant

SummarySoil solarization and grafting onto a resistant tomato rootstock (‘Brigeor F1‘), and the integrated use of both methods were evaluated in four field trials carried out in Cyprus, for management of soil-borne pathogens and pests of eggplant. Soil solarization was highly effective against Verticillium wilt (V. dahliae) but only partially effective against corky root rot (Pyrenochaeta lycopersici) and root-knot nematodes (Meloidogyne spp.); it also controlled adequately most annual weeds. By contrast, grafting provided complete protection from corky root rot and root-knot, but only partial protection from Verticillium wilt. Complete resistance to nematodes, however, occurred only in trials with greenhouse-grown (winter) crops. In open-field (summer) crops, about 50% of the grafted plants sustained slight nematode infection, apparently because of breakdown of resistance at high soil temperatures. Solarization, or grafting gave significant yield increases over that of the untreated check. However, a combination of both was much more effective than either alone. Together, they provided complete protection from all three diseases. Most importantly, they had an additive effect on yield, resulting in a significant increase over that obtained by either method alone. The average yield (kg plant-1) obtained in two greenhouse trials was 9002E5 for the control, 16.1 for grafting alone, 14.1 for solarization alone and 20.2 for the combination of the two methods. The integrated use of solarization and grafting appears to be a sustainable alternative to methyl bromide fumigation.

Scheduling and Control of Crop Production for Advanced Life Support

Advanced life support systems will support human lives during space journeys. Plants will provide food, consume CO2, produce O2, and clean water within the enclosed systems. Computer models were developed for the purpose of analyzing effects of crop production schemes on food supply and resource requirements and for controlling plant growth and development. An object-oriented approach was used to develop a top-level model for crop production scheme analysis. Another approach developed controlled environment crop growth and development models by modifying open field crop models for formulating model-based control algorithms. This paper presents an overview of these two different approaches.

シロガシラによる露地野菜の被害と防止対策 ２ 防止対策

防鳥ネット,(2cm目合)によるシロガシラ被害防止試験をレタスおよびトマトで行った。レタスの防鳥ネット被覆区は被害がみられなかった。またべた掛区は生育初期に被害がみられたが,生育が進むにつれて目立たなくなった。これに対し,無処理区では定植6日後から被害がみられ,14日後には被害株率が100%に達した。トマトのネット被覆区は被害果率が6.0%であったが,無処理区は68.7%と高く,90%以上の減収となった。トマト果実のビニール袋掛区は被害果が全くみられず,品質的にも問題がな牟った。無処理区では被害果率が60%近くに達し,90%近くの減収を示した。収穫期のトマト畑に簡易捕獲おりを設置し,調査圃場への飛来数と捕獲おりへの侵入数を調査した。1998年1月17日から3月5日の間に345羽が飛来し,62羽が捕獲され,捕獲率は17.9%であった。

シロガシラによる露地野菜の被害と防止対策 １ 被害の実態

シロガシラによる露地野菜の被害と防止対策 １ 被害の実態

In vivo studies on genotoxicity of a soil fumigant, dazomet.

Dazomet is a soil fumigant effective against germinating weed seeds, nematodes, soil fungi, and soil insects. Dazomet is primarily used for preplanting control in tobacco and forest nursery crops and is now marketed for a wider range of open field and greenhouse crops (e.g., vegetables, fruits, ornamental plants, lawns, and turfs). Swiss CD1 male and female mice were intraperitoneally treated with dazomet in order to evaluate its potential genotoxicity. DNA damage activity, namely, DNA single-strand breaks, DNA adducts, and increased micronuclei frequency due to treatment with the soil fumigant was observed in the experimental animals. Dose-dependent DNA adduct formation was detected in the liver, kidneys, and lungs of mice. DNA adduct levels in these three organs were 6.0 +/- 0.4 (SD), 4.8 +/- 0.1 (SD), and 2.2 +/- 0.4 (SD) adducts/10(8) nucleotides, respectively, at the highest dose of the soil fumigant tested (90 mg/kg). No adduct formation was observed in control mice. A significant increase in DNA single-strand breaks was detected in the liver and kidneys of mice treated with 100 mg/kg of dazomet (P < 0.05). A significant increase in micronuclei frequency was observed in the bone marrow of mice treated with 100 mg/kg of dazomet (P < 0.05).

Biological and molecular characterization of Tomato spotted wilt Virus in Israel

Received April 24, 1997; received in final form June 29, 1997. Symptoms resembling tomato spotted wilt virus (TSWV) infections were documented among ornamental and vegetable crops in commercial greenhouses and open fields in Israel. Plants exhibiting these symptoms were collected from January 1992 to December 1996. Among cultivated plants analyzed for TSWV by enzyme-linked immunosorbent assay (ELISA), 19 species representing five families were found to be infected; natural infection was also recorded in six plant species of weeds. Virus identity was characterized by host range, serology and electron microscopy. Serological reaction with the isolates, found in Israel, using antisera from different sources as well as the sequence analysis of the nucleocapsid gene, demonstrated that the Israeli isolates of TSWV are a member of tospovirus serogroup I, type I (BR-01 strain). No virus transmission was found in seeds collected from virus-infected vegetable and ornamental crops. A non-radioactive molecular probe derived from the cloned nucleocapsid isolate enables specific detection of the virus in crude sap from infected plants. The detection of TSWV in Israel constitutes a severe potential threat to the ornamental and vegetable industry.

Open Field Farming in the Yakima Valley, Washington

was not among the first hundred. Sheep and turkey production has increased as well. Several factors combined to account for these increases: (1) During the past decade the Roza Project has been completed adding 72,000 acres to the irrigated land of the valley. Much of this new land is not suitable for fruit growing. (2) Removal of many of the high cost apple orchards in the Lower Valley during the 1930's made available land for open field crops. (3) Decreases in acreage planted to several low income crops, such as alfalfa and grains, and a shift to higher income crops also have been important. For example, Yakima County declined from fifth place in alfalfa production in 1940 to tenth in 1945.