Field experiments designed to determine the efficacy and interaction of hexazinone [(3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] and nitrogen on weeds and lowbush blueberry [Vaccinium angustifolium (Ait.)] growth and yield were established at five locations in 1980 and 13 locations in 1981. Hexazinone was applied after pruning, preemergence with nitrogen, using a split-block design, with locations serving as replications. Grasses, goldenrod (Solidago spp.), and meadowsweet [Spiraea latifolia (Ait.) Borkh. # SPVLF] were reduced significantly as the rate of hexazinone was increased. Blueberry injury, plant stand, number of flower buds, and yield all increased with increases in hexazinone rate. Variations in blueberry yields occurred among locations due to differences in plant stand and productivity, as well as climatic and edaphic factors. Within each nitrogen rate, increases in the rate of hexazinone resulted in a quadratic increase in blueberry yield. Within the hexazinone treatments, increasing nitrogen had no effect on yield. Blueberry yield reached a maximum of 3926 kg/ha at a hexazinone rate of 1.83 kg/ha. Partial budgeting was used to evaluate the effect of combinations of hexazinone and nitrogen on net income. Response function analysis determined yield and profit-maximizing combinations of hexazinone and nitrogen. Partial budgeting indicated that hexazinone alone or combined with nitrogen increased net income, but nitrogen without hexazinone decreased net income. Response function analysis indicated that hexazinone at 1.79 kg/ha without nitrogen maximized profits.

Texas panicum (Panicum texanum Buckl. # PANTE) is a native of the Southwest, now increasing as a weed throughout the southern United States, whereas wild proso millet (Panicum miliaceum L. # PANMI) is an introduced weed currently increasing in importance in the northern Midwest. In controlled-environment chambers, both species produced more tillers, greater leaf area, and more total dry weight at 30/24 C day/night (simulated growing season temperature in Georgia) than at 24/18 C (simulated growing season temperature in Minnesota). Texas panicum accumulated more dry matter at 30/24 C than did wild proso millet, while wild proso millet accumulated more dry matter at 24/18 C than did Texas panicum. When the two species were grown together, Texas panicum was the superior competitor at 30/24 C while wild proso millet was superior at 24/18 C. Exposure to short photoperiods at an intermediate temperature of 27/21 C accelerated flowering and limited vegetative growth in both species. In the range of photoperiods (10 to 16 h) examined, wild proso millet always flowered earlier and, consequently, produced less vegetative growth than Texas panicum. Its responses to temperature and photoperiod indicate that wild proso millet probably would be competitively inferior to Texas panicum and other adapted grass weeds in the southern United States.

Plant growth, stem numbers per plant, receptacle diameters, number of Rhinocyllus conicus Froelich (Coleoptera:Curculionidae) larval cells per seed head, and mortality of the weevil within cells were monitored in infestations of the thistles Carduus thoermeri Weinmann and C. macrocephalus Deft. Both species of thistle provided similar seed head area for weevil development, and no differential effects on the biology of R. conicus were detected.

Field research was conducted at two locations in 1982 and 1983 to evaluate the competitiveness of coffee senna (Cassia occidentalis L. # CASOC) with cotton (Gossypium hirsutum L.). With season-long competition, each increase of 1 coffee senna plant/7.5 m of row reduced seed cotton by 9 to 117 kg/ha. Each additional week of competition from a dense stand (40 plants/m of row) of coffee senna reduced seed cotton yield by 118 kg/ha and cotton main stem height by 1.25 cm. Neither cotton stand density nor fiber properties were affected by coffee senna density or duration of competition. Seed cotton yields and main stem heights obtained when cotton was kept weed free for 6 weeks after cotton emergence were not significantly different from those kept weed free for 8, 10, or 14 weeks. Coffee senna dry-matter production was essentially zero when cotton was maintained weed free for 8 or more weeks.

Soil characteristics, elevation, annual precipitation, potential evapotranspiration, length of frost-free season, and mean maximum July temperature were estimated for 116 established infestations of spotted knapweed (Centaurea maculosa Lam. # CENMA) in Montana using basic land resource maps. Areas potentially vulnerable to invasion by the plant were delineated on the basis of representative edaphic and climatic characteristics. No single environmental variable was an effective predictor of sites vulnerable to invasion by spotted knapweed. Only a combination of variables was effective, indicating that the factors that regulate adaptability of this plant are complex. This technique provides a first approximation map of the regions most similar environmentally to infested sites and, therefore, most vulnerable to further invasion. This weed migration prediction technique shows promise for predicting suitable habitats of other invader species.

The effect of Jerusalem artichoke (Helianthus tuberosus L. # HELTU) density and duration of interference in soybeans [Glycine max (L.) Merr. ‘Hodgson 78’] was investigated in two studies. Jerusalem artichoke densities of 1, 2, and 4 tubers/m of row reduced soybean seed yield by 31, 59, and 71%, respectively. Soybean height, branches/plant, pods/plant, and seed weight were usually reduced by all three weed densities. Soybean leaf area and relative growth rates were reduced by densities of 2 and 4 tubers/m of crop row, and net assimilation rate (NAR) was reduced by 4 tubers/m of crop row. Jerusalem artichoke interference at 4 tubers/m of row for 4, 6, 8, and 20 weeks (full season) reduced soybean yields 9, 10, 38, and 82%, respectively. Branches/plant, pods/plant, and seeds/plant were reduced after 8 weeks of interference. These results suggest that Jerusalem artichoke is highly competitive with soybean and should be controlled within 6 weeks after planting.

Chemicals that stimulate germination of curly dock seed (Rumex crispus L. # RUMCR) and urediniospores of curly dock rust [Uromyces rumicis Schum. (Wint.)], an obligate parasite of this weed, were studied and compared. Methyl salicylate, benzyl cyanide, and benzonitrile were the best stimulators of germination of curly dock seed. The compounds tested were most effective at concentrations ranging from 250 to 1000 μl/L. A 500 μl/L concentration of methyl salicylate caused 99% of the curly dock seed to germinate. Exposure to volatiles from 10 μl methyl salicylate or octyl cyanide for 16 to 24 h was required for maximum stimulation of curly dock seed germination in 10 days. Benzonitrile, methyl-2,4-dihydroxybenzoate, 3-cyanophenol, 2-heptanone, and benzaldehyde were the most effective of 45 compounds tested on urediniospores of curly dock rust. Benzonitrile was most active of 19 compounds tested on both seed and spores. Benzyl cyanide, 4-methoxybenzonitrile, benzaldehyde, and methyl 2,4-dihydroxybenzoate also were active on both propagules.

Thirty-eight percent of monoecious hydrilla [Hydrilla verticillata (L.f.) Royle # HYLLI] grown from tubers produced new tubers after 28 days exposure to a 10-h photoperiod. One hundred percent of the plants grown at a 10-h photoperiod produced tubers by 56 days while only thirty-eight percent of those grown at a 12-h photoperiod did so. Plants grown at 14- or 16-h photoperiods did not produce tubers. Tubers appeared to be produced at the expense of new root and shoot tissue. Dioecious hydrilla (female) grown under similar conditions did not produce tubers by 56 days at any photoperiod examined. Relative growth rates (total dry weight) for both types did not differ with photoperiod and ranged between 81 ± 63 and 284 ± 52 mg·g-1·wk-1 (regression coefficient ± standard error; n = 30). In general, total chlorophyll (a+b) was greater for dioecious than for monoecious plants. The ratios of chlorophyll “a” to chlorophyll “b” and carotenoids to chlorophyll a changed with increasing photoperiod and plant age in a similar manner for both monoecious and dioecious plants.

A 3-yr experiment and a 1-yr experiment in continuous winter wheat (Triticum aestivum L. ‘Newton’) and two 3-yr experiments in continuous grain sorghum [Sorghum bicolor L. (Moench.) ‘Co-op SG-10’ or ‘DeKalb DX-42Y’] were conducted to evaluate selected foliage-applied herbicides for control of honeyvine milkweed [Ampelamus albidus (Nutt.) Britt # AMPAL]. Glyphosate [N-(phosphonomethyl)-glycine] applied at 3.4 kg ae/ha, glyphosate plus dicamba (3,6-dichloro-2-methoxybenzoic acid) applied at 1.7 plus 0.6 kg ae/ha, and glyphosate plus 2,4-D [(2,4-dichlorophenoxy)acetic acid] applied at 1.7 plus 1.1 kg ae/ha in summer between harvesting and planting winter wheat and in spring prior to planting grain sorghum effectively reduced honeyvine milkweed regrowth 1 yr after initial application in both cropping systems. One or two additional annual applications did not provide complete control in either cropping system. Applications of 2,4-D at 2.2 kg ae/ha dicamba at 1.1 kg ae/ha and 2,4-D plus dicamba at 1.1 plus 0.6 kg ae/ha were effective if applied consecutively for 3 yr in continuous winter wheat but not in continuous grain sorghum.

Legal protection of intellectual property is a requisite to the commercialization of the intellectual property and to the conferring of proper reward to the true owner of the property. Simplistically stated, this situation with regard to intellectual property is no different from the legal protection of a variety of properties, for example, home, land, or automobile. Laws have been established in the various countries of the world that are structured specifically to attain the desired goal of legally protecting property interests. In the intellectual property field, wherein we talk about property such as new inventions, we enter an area of not only protecting the legal rights of the property owner but also insuring the position of the public with respect to the eventual unlimited use of new inventions.

Teliospores of Sphacelotheca holci Jack. [= S. cruenta (Kuhn.) Potter] infected johnsongrass [Sorghum halepense (L.) Pers. # SORHA) systemically after inoculation of cut stems in greenhouse studies. A preliminary host range test in the greenhouse revealed that no infection occurred on four varieties of sorghum (S. vulgare L.) and three cultivars of sudangrass (S. Sudanese L.). Infected johnsongrass plants grown in the greenhouse exhibited reduced vegetative growth and altered morphological characteristics compared to healthy johnsongrass plants. The aboveground biomass and lateral rhizome expansion of smutted johnsongrass field transplants were significantly lower than that of uninfected plants. Significant correlations between fraction of johnsongrass stems infected and plant weight, and basal area of plants were observed in field studies. Corn (Zea mays L.) and alfalfa (Medicago sativa L.) grown in competition with johnsongrass, and johnsongrass infected with S. holci reduced the aboveground biomass and rhizome length of johnsongrass plants significantly, compared to that of uninfected johnsongrass plants grown alone in greenhouse studies. Uninfected johnsongrass plants also exhibited higher plant weight than infected plants when both were grown in competition with alfalfa, regardless of the alfalfa planting density in the greenhouse or when measured after 3 months in field trials.

A field experiment was conducted to determine the influence of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] and/or chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl)benzenesulfonamide} on germination, coleoptile growth, and mineral accumulation of seed from treated parent plants. The herbicides were applied postemergence in the spring to ‘Vona’ and ‘Centurk’ winter wheat (Triticum aestivum L.). The rate of metribuzin was 360 g ai/ha, with chlorsulfuron applied at 18, 35, or 70 g/ha. Metribuzin reduced grain yields of both varieties approximately 40%, whereas chlorsulfuron at the higher rates reduced grain yields of only Vona. Seed germination was not affected by either herbicide, but metribuzin, when applied alone, reduced coleoptile growth of Vona seed. The addition of chlorsulfuron to metribuzin eliminated this growth reduction. The mineral concentration of the seed of both varieties indicated that metribuzin and chlorsulfuron did not affect mineral translocation to the seed by the parent plant.

Broadleaf signalgrass [Brachiaria platyphylla (Griseb.) Nash # BRAPP has recently become the dominant annual grass in certain fields of the North Carolina Coastal Plains. Previously, fall panicum (Panicum dichotomiflorum Michx. # PANDI) and large crabgrass [Digitaria sanguinalis (L.) Scop. # DIGSA] were the dominant annual grasses in the region. One of the possible reasons for the observed population shift could be production of inhibitors or stimulators by one species that affects the population dynamics of the other species. Studies were initiated to evaluate the effects of broadleaf signalgrass, large crabgrass, and fall panicum residue, applied as a mulch or soil incorporated, on five indicator species: the three weeds themselves, corn (Zea mays L.), and soybean [Glycine max (L.) Merr.]. At expected residue levels, the degree of inhibition or stimulation from fall panicum and broadleaf signalgrass was determined to be significant for some indicator species. When such responses were seen, the amount of residue necessary to produce these results was usually within the concentrations normally observed in field situations. Based on these results, it appears that the observed population shift is partially mediated by the production of inhibitors or stimulators through plant residue. Other factors such as differential herbicide selectivity and crop rotation are being investigated.

An experiment was conducted at five locations in Nebraska to determine the extent of demise of weed seed in soil when seed production was eliminated from 1975 through 1979 in corn (Zea mays L.). Weed yields, weed seed production, and corn yields were determined under four weed management levels in 1980. Annual broadleaf weed seed were more prevalent than grass seed in cultivated soil throughout the study. The population of viable weed seed in soil declined 95% during the 5-yr period that weed seed production was eliminated. Weed seed buildup recovered to within 90% of the 1975 level during 1980 at Concord and Clay Center but remained low at Lincoln, North Platte, and Scottsbluff. Thus, seed longevity in soil was sometimes sufficient to withstand modern weed control methods and still reinfest a field after 5 yr of eliminating weed seed production. Corn yields were maintained 1 yr with minimum weed management effort following 5 yr of no weed seed production.

Although herbicides are designed to have no effects on the crops in which they are used, crop damage can occur, especially when overdoses are used or if chemicals are applied at an inappropriate time. Usually the resulting damage is recognized as foliar symptoms but roots may be severely affected as well.

Several herbicides were toxic to barnyardgrass [Echinochloa crus-galli (L.) Beauv. # ECHCG] when applied as a soil treatment at 0.56 kg ai/ha to a sandy loam soil with 0.8% organic matter. At this application rate, haloxyfop {methyl ester of 2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, CGA-82725 {2-propynyl ester of 2-[4-[(3,5-dichloro-2-pyridinyl)oxy] phenoxy] propanoate}, and DPX-Y6202 {ethyl ester of 2-[4-[(6-chloro-2-quinoxalinyl)oxy]-phenoxy] propanoate} provided the greatest persistence of activity. At 31, 28, and 25 days after treatment with these herbicides, respectively, barnyardgrass growth was still inhibited by 50%. Soil activity and persistence of fluazifop {butyl ester of (±)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} increased following soil sterilization. Covering the soil surface with vermiculite prior to treatment intercepted the spray and significantly reduced control of 4- to 6-cm-tall barnyardgrass plants with fluazifop.

Experiments were conducted to investigate enhanced biodegradation of carbamothioates and to evaluate the effect of microbial inhibitors on the efficacy of butylate [S-ethyl bis(2-methylpropyl)carbamothioate], EPTC (S-ethyl dipropylcarbamothioate), and vernolate (S-propyl dipropylcarbamothioate) in soils that had received butylate treatment in previous years (butylate-history soils). Inhibitors used were fonofos (O-ethyl-S-phenylether phosphonodithioate) and R-33865 (O,O-diethyl-O-phenylphosphorothioate). R-33865 and fonofos significantly improved control of large crabgrass [Digitaria sanguinalis (L.) Scop. # DIGSA] with butylate and EPTC in corn (Zea mays L. ‘Coker 21’). Bioassay data reflected more residual phytotoxicity from butylate and EPTC when these herbicides were combined with the microbial inhibitors. In butylate-history soils planted to soybeans [Glycine max (L.) Merr. ‘Wright’], R-33865 did not improve the efficacy of vernolate. These results indicated some cross-adaptation of the butylate-adapted microorganisms for EPTC, but no cross-adaptation was detected for vernolate. Under laboratory conditions, 14C-butylate was degraded more rapidly to 14CO2 in butylate-history soils than in non-butylate-history soils.

Clods of three sizes (1.5-, 3.3-, and 5.3-cm diameter) and two hardnesses [soft (0.3 MPa) and hard (2.2 MPa)] were made by incorporating seed from one of the five following weed species: corn poppy (Papaver rhoeas L. # PAPRH), shepherdspurse [Capsella bursa-pastoris (L.) Medic. # CAPBP], smooth crabgrass Digitaria ischaemum (Schreb.) Muehlenb. # DIGIS], common lambsquarters (Chenopodium album L. # CHEAL), and Canada thistle [Cirsium arvense (L.) Scop. # CIRAR], listed by increasing seed size. Under conditions of this experiment, higher germination occurred with larger seed. The higher germination was connected with fewer dormant seed remaining in the clods. Germination significantly decreased (13%) in the larger soft and hard clods with the smaller seed sizes (less germination associated with more dormant seed remaining in the clod). Germination of the two larger seed decreased (23%) only in the larger soft clods but was less significant with both small seed. Non-emerged seedlings increased with larger clods and was most significant with the three large seed in the hard clods and absent with the three large seed in the soft ones. On the average, 70% of the germinated seed emerged. Differences in germination as well as in nonemerged seedlings caused decreased emergence on larger clods. Clod influence in germination and emergence was explained by the volumes of the clod layers involved, and in some comparable aspects corresponded with volumes (depths) of soil layers.

Absorption and translocation of 14C following 14C-fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} butyl ester and 14C-sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} application to oats (Avena sativa L. ‘Lyon’) was greater when the herbicides were applied with oleic acid, linoleic acid, or fatty acid methyl esters compared to various triglycerides. The methyl esters of stearic, oleic, linoleic, and linolenic acids enhanced 14C absorption and translocation when applied with 14C-fluazifop and 14C-sethoxydim, except that the methyl ester of stearic acid did not enhance 14C absorption and translocation when applied with 14C-sethoxydim. The absorption and translocation of 14C following the application of 14C-CGA-82725 {(±)-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy] propanoic acid)-2-propynylester}, 14C-diclofop {(±)-2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid}, 14C-fluazifop, and 14C-sethoxydim were generally enhanced equally or greater by the methyl ester of sunflower (Helianthus annum L.) oil than by petroleum oil additive or once refined sunflower oil. Methylated sunflower oil was equally or more effective as an additive than petroleum oil in enhancing grass control with fluazifop and sethoxydim in a field experiment.