Darbo tikslas – įvertinti įsėlinių tarpinių augalų, piktžolių ir kaupiamųjų augalų konkurencingumą ekologinio ūkininkavimo sąlygomis bei mulčiavimo technikos pritaikymas tarpueilių mulčiavimui. Įsėlinių tarpinių augalų („gyvojo mulčio") ir piktžolių konkurencingumo dėsningumai kaupiamųjų augalų pasėliuose nėra išsamiai ištirti. Pasaulyje šia linkme tyrimai yra tik pradėti. Mėginta mūsų iškeltas problemas spręsti daržininkystėje ir auginant kai kuriuos grūdinius javus. Gauti pirmieji teigiami rezultatai. Mūsų tyrimuose bandymo schema buvo išplėsta, tiriama daugiau rūšių įsėlinių augalų, įvertinamas dirvoje esančių maisto medžiagų balansas. Taip pat buvo įvertintas kaupiamųjų augalų mulčiavimas, piktžolių - įsėlinių augalų konkurencingumas. Šios srities tyrimai Lietuvoje vykdyti, tačiau dažniausiai buvo tirtas posėlinių ir įsėlinių augalų poveikis juos panaudojant žaliajai trąšai. Mūsų tyrimuose buvo atskleisti unikalios kaupiamųjų augalų auginimo technologijos ekologinio ūkininkavimo sąlygomis ypatumai – vietoj įprasto tarpueilių purenimo taikyti tarpueilių mulčiavimą tarpiniais augalais. Atlikus eksperimentinius tyrimus skirtingais kukurūzų vystymosi tarpsniais, kukurūzų tarpueiliuose nustatyta gyvojo mulčiaus ir piktžolių masė (g∙m-2) bei kaupiamųjų augalų konkurencingumas, taip pat nustatyta fotosintetinė aktyvioji spinduliuotė (FAR), tenkanti augalams žemės paviršiuje bei dirvos drėgnis 0–10 cm ir 10–20 cm gylyje. / The aim of the research was to assess the competiveness of the undercrops, weeds and row crops under the conditions of organic farming using the interrow mulching techniques. There is no thorough research on the peculiarities of the undercrops (living mulch) and weed competitiveness in the row crops. Scientists all over the world have only started investigating this subject. The study attempts to utilize the researched subject in gardening and growing some of the grain crops. The first positive results were obtained. The testing scheme of our research was extended by investigating more species of undercrops, assessing the balance of the soil nutrients. The competitiveness of cumulative plants mulching with weeds and undercrops was evaluated. There is some research on this subject in Lithuania, but most of it deals with the investigation of aftercrop and undercrop plants and implications for their use as green manure. The studies revealed the unique technologies of the row crop production under the conditions of organic farming moreover, instead of the usual loosening the interrow mulching was applied. The experimental research has identified the living mulch and weed weight (g∙m-2)in the interrows at different stages of maize growth, row crop competitiveness, photosynthetic active radiation (PAR), which falls on plants and soil surface humidity in 0 to 10 cm and 10–20 cm depth.

Reducing tillage in Canadian organic cropping systems is a priority to preserve soil quality and increase long term sustainability. Novel methods for management of cover crops offer farmers the opportunity to reduce both tillage and herbicide use during this phase of the crop rotation but require further investigation across a range of cropping systems. The objective of this study was to compare the blade roller, flail mower and wide blade cultivator (noble blade) with standard tillage for management of an annual pea-barley (Pisum sativum L. – Hordeum vulgare L.) green manure in the Canadian prairies. The experiment was conducted twice at Carman, Manitoba (long-term organic management) and Lethbridge, Alberta (previous herbicide and fertilizer use) from 2010-2012. The green manure was planted in spring of year 1 and grown until pea full bloom when five management treatments were applied; 1) standard tillage with a field disc 2) blade roller, 3) blade rolled once plus tillage in late fall and spring, 4) wide blade cultivator and 5) flail mower. Spring wheat (Triticum aestivum L.) was planted in spring of year 2. The effect of management treatment on surface residue, soil nitrogen, soil microclimate, weed population dynamics and subsequent spring wheat yield was evaluated. At Carman, managing green manure without tillage (blade roller or flail mower) significantly increased winter annual and perennial weed pressure and reduced soil nitrate availability; these factors contributed to wheat yield reductions in both years compared to standard tillage. Wide blade cultivation and blade rolling plus tillage maintained crop yield at one and both years, respectively, compared to tillage. Without sufficient mulch for weed suppression, soil disturbance was required to control weeds and ensure adequate nitrogen uptake in the crop. Replacing one tillage operation with blade rolling reduces energy costs and erosion risk without sacrificing yield. At Lethbridge, previous herbicide and fertilizer use masked the effect of green manure management. Markedly different results from Carman and Lethbridge emphasize that the adaptability of reduced tillage green manure management is site-specific due to differences in climate and cropping history. This research highlights important differences in the efficacy, erosion risk, weed control, nitrogen availability, main crop yield and energy savings associated with each management method.

Amaranthus retroflexus L. (redroot pigweed) is a major weed of many crops in North America including corn, soybean, and potato. It can be readily controlled by chemical and cultural methods. However, some populations of A. retroflexus have developed resistance against the application of triazine herbicides. Biololical control could be an alternative method to control this weed species. In 1990, a Macrophoma sp. causing foliar lesions was isolated from redroot pigweed and the potential of this plant pathogenic fungus as a mycoherbicide was evaluated. Large numbers of infective propagules were produced in solid substrate fermentation with chickpeas. When inoculated with 10$ sp8$ or 10$ sp9$ conidia m$ sp{-2}$, plants at the cotyledon to 2-leaf stage showed the most severe damage. Disease developed over a wide range of dew period durations (6 hr to 24 hr) and temperature regimes (14 C to 26 C), and the most rapid and destructive disease development occurred following a 24-hr dew period at 18 C. In controlled environment studies, this Macrophoma sp. was pathogenic to the genus Amaranthus and the closely related genus Celosia.

In a survey conducted in Zimbabwe in 1993, waterhyacinth was present in seven out of the eight provinces. No control measures were imposed on 35% of the infested dams and 61% of the infested rivers, while in 47% of the infested dams and 11% of the infested rivers control of waterhyacinth was being attempted with a combination of 2,4-D and mechanical control methods. The population of Neochetina eichhorniae and N. bruchi declined during the period 1993 to 1995 in the Hunyani River system. Several fungi were isolated from diseased waterhyacinth, and Fusarium moniliforme (isolate 2ex 12), F. solani (isolates 5a ex25 and 2a3), and F. pallidoroseum (isolate 3ex1) were found to be the most pathogenic. Large numbers of viable conidia were produced in shake-flask liquid fermentation with modified Richard's medium and in solid fermentation with food grains. Conidia production in straw was poor with the exception of waterhyacinth straw. Host range studies conducted in pots and in the field indicated that Commelina benghalensis was moderately susceptible to both isolates of F. solani in the field, while Setaria verticilata grown in pots was moderately susceptible to isolate 2a3. Brassica rapa and Crotalaria juncea grown in pots were moderately susceptible to F. moniliforme but they showed no infection in the field. Fifty-nine additional plant species of ecological and agricultural importance were not susceptible to the Fusarium species. When F. solani, F. pallidoroseum and Neochetina spp. were used individually in ponds, they did not control waterhyacinth. When the fungi were combined with Neochetina spp., the area covered by waterhyacinth and the volume of waterhyacinth were significantly reduced.

Phomopsis convolvulus Ormeno, a foliar pathogen of field bindweed, is a good candidate to be developed as a bioherbicide. Large numbers of infective propagules were produced in shake-flask liquid fermentation with modified Richard's (V-8) medium and in solid-substrate fermentation with pearl barley grains. In complex liquid media, pycnidium-like structures were observed. Most conidia stored at $-$70$ sp circ$C remained viable and virulent for at least six months. / In controlled environment studies, a minimum of 18 hr of dew was required for severe disease development on inoculated plants. The addition of gelatin, Sorbo $ sp{ rm TM}$, or BOND$ sp{ rm TM}$ to the inoculum did not enhance the disease under various leaf wetness periods. A continuous dew period of 18 hr was superior to the cumulative effect of three interrupted 6 hr dew periods. Secondary inoculum was produced on diseased plants placed under moist conditions for 48 hr or more. / In greenhouse experiments, seedlings at the cotyledon and 3- to 5- leaf stage were severely diseased and killed when inoculated with 10$ sp9$ conidia/m$ sp2$. This inoculum density adversely affected the regenerative ability of 4 wk old seedlings and established plants, but few plants were killed. Inoculation of the healthy regrowth from plants previously inoculated with the fungus resulted in much less disease symptoms than expected.

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Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 76-80. / v, 80 l mounted illus., tables

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