Field and controlled environment experiments were performed to assess the preemergence activity of the fungal pathogen, Phomopsis convolvulus Ormeno to control Convolvulus arvensis L. (field bindweed). A granular barley formulation of the fungal inoculum applied onto the field soil surface resulted in dramatic aboveground biomass reductions of both C. arvensis seedlings (94--100%) and regrowth from established plants (53--98%). Under field conditions, surface applications of the granular formulation resulted in greater biomass reductions (93--100%) compared with soil incorporation of the granules (31--97%). Rate of soil applied granules of P. convolvulus did not affect the level of weed control and 90--100% C. arvensis biomass reductions were obtained for all rates used (30 g, 20 g, and 10 g 0.25m--2 plot). The use of two different planting substrates in controlled environment studies led to major differences in C. arvensis disease development. With an inoculum application on the day of sowing, 81% mortality was obtained for seedlings grown in a sandy loam field sod compared with 50% of seedlings grown in a prepared peat moss medium. The susceptibility of C. arvensis biotypes from various geographic locations to P. convolvulus was similar following post-emergence, foliar inoculum applications. Significant above-ground (65--100%) and new root growth (56--72%) biomass reductions of established plants were obtained for two selected biotypes (Greece, USA-Montana) subjected to a preemergence granular inoculum application. In the presence of spring wheat (Triticum aestivum L.), field efficacy of P. convolvulus was enhanced and aboveground biomass of inoculated C. arvensis plants was reduced by 98% compared with inoculated C. arvensis plants grown in pure stand.

Canada-thistle and field bindweed are two troublesome weeds in Utah. Jensen, in cooperation with county weed committees, conducted a weed survey in the state. Seriousness of weeds was listed by counties. Field bindweed was considered to be either a serious or very serious weed in every county except one, and Canada-thistle was classified in these two categories in over one-half of the counties.

No description available.

No description available.

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.

Field bindweed (Convolvulus arvensis L.) is a noxious perennial weed of many fallow and cropland fields all over the world. Present control methods are not satisfactory for field bindweed. Metsulfuron, 2[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid, is a new herbicide that has been shown to have activity on bindweed especially when tank mixed with other herbicides. This study was conducted to investigate the field performance and some physiological effects of metsulfuron on field bindweed. Neither metsulfuron alone nor metsulfuron combinations gave persistent control of field bindweed. Metsulfuron usually increased the activity of other bindweed herbicides. Herbicide application to field bindweed in the full bloom growth stage did not control the weed as well as the same treatments in the prebloom growth stages and treating regrowth the fall after tilling bindweed in full blossom. Application of metsulfuron at full bloom decreased seed weight, seed size seed viability and seedling vigor of field bindweed but did not alter seed set. Metsulfuron at 23 g/ha and above caused unacceptable injury to barley (Hordeum vulgaris L.) and oats (Avena sativa L.). Higher rates of metsulfuron resulted in greater phytotoxicity. Metsulfuron stopped photosynthesis of field bindweed within two weeks regardless of herbicide dosage used. Field bindweed seedlings were observed growing in the field under light intensities of 28 to 62 μmoles m-2 s-1 which was below the light compensation point obtained for greenhouse grown bindweed plants (about 65 μmoles m-2 s-1). Higher quantities of 14C labelled metsulfuron per mg plant dry weight were recovered in the above treated leaf sections than in any other parts of bindweed plants. Metsulfuron applied as a foliage spray two days prior to administering 14C metsulfuron significantly increased absorption to the radiolabelled herbicide in field bindweed plants.

Onion thrips (Thrips tabaci) and Iris Yellow Spot Virus (IYSV) constitute a pest complex of global concern for allium growers. Yield losses due to onion thrips alone can be heavy, and in tandem with IYSV, these losses can be complete. This study was one phase of a multi-phase research project intent on exploring the potential drivers of thrips and virus infestation in onion. Preliminary observations in participating growers’ fields in northern Utah pointed towards a potential link between weedy field borders and thrips/IYSV infestation in onion. Field work was carried out at the Kaysville experiment station examining the possible relationships between thrips and IYSV incidence in onion and the presence of adjacent weed populations. This research was conducted with the intent of guiding growers’ decisions regarding field border management, and to provide additional insights into onion thrips behavior. While implications for growers remain unclear, thrips preferences regarding host plant utilization were identified, as well as preliminary evidence of additional plant species capable of hosting IYSV.