The growth of tomato (Lycopersicoti esculentum Mill., var. Heinz 1350) plants was enhanced by low concentrations of both N,N-dimethyl-2,2-diphenylacetamide (diphenamid) and the filtrate from two fungal species Trichoderma viride (Tode) Harz and Aspergillus candidus Link. High concentrations of the filtrate from these fungi inhibited the growth of tomatoes, but this was overcome by the addition of diphenamid. Diphenamid also increased the growth of these two fungi.

The foliage and roots of Canada thistle (Cirsium arvense (L.) Scop.) readily absorbed 2-methoxy-3,6-dichlorobenzoic acid (dicamba) after which it was translocated by both phloem and xylem. The results are in harmony with a source-to-sink system of dicamba translocation in the phloem. Following foliar application, small amounts of dicamba were exuded by the roots into surrounding soil. Dicamba tended to accumulate in young, growing leaves following both foliar or root uptake. Leaves, but not roots, retained a substantial portion of the dicamba taken up. After 54 days, 63.1% of the recovered radioactivity in the treated leaf was still in the form of unaltered dicamba. The remaining 36.9% was in the form of an unidentified product. In other plant parts, much less change occurred. During a 54-day period, one-fifth of the dicamba applied was recovered as radioactive CO2.

Growth chamber and field studies were conducted to investigate the possibility of an interaction between the herbicides 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline (nitralin), a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin), 3- (m-tri-fluromethylphenyl)-1,1-dimethylurea (fluometuron), and 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine (prometryne), and the seedling disease organism Rhizoctonia solani Kuehn in cotton (Gossypium hirsutum L.). When high levels of trifluralin or prometryne were used in the growth chamber, an interaction with the pathogen that was injurious to the cotton occurred. Prometryne and fluometuron produced an antagonistic effect on R. solani.

Under field conditions, R. solani usually caused cotton injury. Interactions injurious to the cotton occurred between trifluralin and a low level of R. solani and between nitralin and a high level R. solani infestation. No interactions occurred with fluometuron or prometryne. In all instances, the effect occurred only when the herbicides were being used at high rates.

We studied 4-amino-3,5,6-trichloropicolinic acid (picloram) alone and in combination with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) or 1,1′-dimethyl-4,4′-bipyridinium salt (paraquat) for control of several greenhouse, nursery, and natural-grown, woody plant species. Picloram:paraquat combinations improved the control of some species such as yaupon (Ilex vomitoria Ait.) as compared to picloram alone at equal rates; but it had an antagonistic effect on huisache (Acacia farnesiana (L.) Willd.) and honey mesquite (Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell). Evaluation of picloram: 2,4,5-T combinations suggested that 2,4,5-T sometimes could be added in equal amounts to picloram to increase control or reduce picloram rates proportionately on huisache, honey mesquite and live oak (Quercus virginiana Mill.).

Spray and granular forms of isopropyl N-(3-chlorophenyl)-carbamate (CIPC, ethyl N,N-dipropylthiocarbamate (EPTC), a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) and 2,4-bis(isopropylamino) -6-methylmercapto-s-triazine (prometryne) were incorporated preemergence to barnyardgrass Echinochloa crusgalli (1.) Beauv.) and broadleaf weeds with a rotary tiller, wheel hoe, rotary spike, or row wheel into pre-irrigated or dry soil at three locations. The locations varied in type of soil, climatic conditions, and the species of broadleaf weeds. Rotary tiller incorporation generally resulted in best weed control with both spray and granular forms under all conditions. Herbicides usually performed best in pre-irrigated soil. Sprays and granules were equal in performance at coastal and intermediate locations; granules were more effective in the desert location. Herbicidal effectiveness was influenced by method of incorporation, form of treatment, soil moisture, environmental location, and weed type.

Large Crabgrass (Digitaria sanguinalis (L.) Scop.) and barnyardgrass (Echinochloa crusgalli (L.) Beauv.) plants were grown from seedlings to maturity under five light qualities of equal energy levels. For crabgrass, both fresh and dry weight yields of plant tops grown under red light and under cool white light were significantly greater than those under green, yellow, or blue light. Length of stem followed this same order. Effects of light quality on reproduction were not as consistent; green and blue light caused the largest numbers of seed heads to form, while yellow light delayed flowering and resulted in the least number and weight of seed heads. Somewhat similar responses to light were found with barnyardgrass plants, except that yields under yellow light were close to those under red light for this species. Blue light caused smallest plants in both kinds of weeds.

In 1965 and 1966, alfalfa (Medicago sativa L., var. Cayuga) and birdsfoot trefoil (Lotus corniculatus L., var. Viking) were seeded in soil treated just before planting with ethyl N,N-dipropylthiocarbamate (EPTC). To determine herbicidal interaction on a field scale, 4,6-dinitro-o-Sec-butylphenol (DNBP) was applied as a postemergence treatment. No significant interaction of EPTC and DNBP was evident on legume or weedy grass stands on yield. Interaction of EPTC and DNBP on control of annual broadleaf weeds was noted 1 year but not the second. DNBP but not EPTC significantly reduced birdsfoot trefoil stands during both years and reduced alfalfa stands 1 year but not the other. EPTC controlled annual and perennial weed grasses and DNBP controlled annual broadleaf weeds successfully. The incorporation of EPTC in soil before planting alfalfa and birdsfoot trefoil followed by a postemergence DNBP treatment was considered to be a practical weed control method.

We studied the uptake and transport of 4-amino-3,5,6-trichloropicolinic acid (picloram) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) alone and in combination and in the presence of 1,1′-dimethyl-4,4′-bipyridinium salt (paraquat) by honey mesquite (Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell), huisache (Acacia farnesiana L. Willd., yaupon (Ilex vomitoria Ait.), and bean (Phaseolus vulgaris L.). Paraquat reduced transport of picloram by mesquite, huisache, and bean. Paraquat increased uptake of picloram by yaupon but did not affect transport. The uptake and transport of 2,4,5-T by mesquite decreased in the presence of picloram, but the uptake and transport of picloram increased in the presence of 2,4,5-T. Increasing ratios of 2,4,5-T:picloram up to 16:1 continued to increased uptake and transport of picloram; the inverse effect occurred for 2,4,5-T when picloram:2,4,5-T ratios were increased.

Five preplant, soil-incorporated herbicides were evaluated over a 2-year period for their effect upon the growth of representative varieties of 15 common species of spring-planted annual flowers. Of these, α,α,α,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) was effective in combining freedom from plant injury with control of weeds. Only in phlox (Phlox nana compacta Nutt., var. Fireball) was growth reduced significantly over the 2-year period by this herbicide at 2 lb/A while petunia (Petunia hybrida, var. Snow Lady) was reduced in 1 of 2 years. N,N-dimethyl-2,2-diphenylacetamide (diphenamid) at 4 and 8 lb/A was effective and ethyl N,N-dipropylthiocarbamate (EPTC) at 4 lb/A was fairly effective, but both were tolerated by fewer flower species. N-(2-mercaptoethyl) benzenesulfonamide S-(O,O-diisopropyl phosphorodithioate) (bensulide) at 10 lb/A and methyl 3,4-dichlorocarbanilate (swep) at 5 lb/A were not phytotoxic to any species but were relatively ineffective in controlling the weeds present.

Purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (Cyperus esculentus L.) tubers were stored at 5 C in soil treated at 0, 2, 3, 4, 6, 8, or 10 lb/A 2,6-dichlorobenzontrile (dichlobenil) for 2, 4, 6, 8, 10, or 12 weeks. Respiration of dormant tubers differed with species, unaffected by period of storage or dichlobenil concentration. Sprouting of untreated tubers decreased from 90% after 2 weeks storage to 43% after 12 weeks. Yellow nutsedge sprout production was uniform in time; purple nutsedge sprouting progressed to an 8-week high. Increased concentrations of dichlobenil progressively inhibited sprouting.

The effects of sublethal and lethal levels of 3-(3,4-dichlorophenyl)-l-methoxy-l-methylurea (linuron) on the uptake of 32P and 45Ca were tested on tomato (Lycopersicum esculentum Mill., var. Kokomo) and parsnip (Pastinaca sativa L., var. Harris Model). Both levels of foliage-applied linuron stimulated the uptake of 32P from nutrient culture solution and its translocation to the leaves. The increased 32P in the leaves of the treated tomato plants was found in the inorganic phosphate fraction. Incorporation of the label in the phospholipid and nucleic acid fractions was decreased slightly. Linuron inhibited uptake and translocation of 45Ca in both plants.

Field studies were conducted over a 2-year period at Urbana, Illinois, to evaluate soybean (Glycine max (L.) Merr., var. Harosoy 63 and Wayne) and weed yields as influenced by row spacing, variety, weed control methods, and 2,3,5-triiodobenzoic acid (hereinafter referred to as TIBA). Soybean yield increased and weed yield decreased as row spacing was decreased. Compared to the yield from 40-inch rows, soybean yield increase was 10, 18, and 20% for 30, 20, and 10-inch rows, respectively. Both cultivation and applications of a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) controlled annual grass weeds at all row spacings. Cultivation controlled broadleaf weeds at all row spacings. Some broadleaf weeds, unaffected by trifluralin, made sufficient growth to impair soybean yields in wide rows but not in narrow rows.

From 1962 to 1967, we evaluated herbicides for control of natural infestations of reed canarygrass (Phalaris arundinacea L.) on canal banks of the Huntley, Montana irrigation project. Two,2-dichloropropionic acid (dalapon) and 3-amino-1,2,4-triazole ammonium thiocyanate (hereinafter referred to as amitrole-T) controlled reed canarygrass. These herbicides were compared with a number of others. Spring foliage treatments with a combination of amitrole-T at 2 1b/A and dalapon or trichloroacetic acid (TCA) at 5 or 10 1b/A were more effective than amitrole-T at 4 1b/A. Amitrole-T was more tolerant to fine grasses such as Kentucky bluegrass (Poa pratensis L.) or redtop (Agrostis alba L.) than dalapon and in some situations it was more desirable than dalapon. Dalapon and TCA were more effective as late fall or early winter treatments to control reed canarygrass during the following growing season. Rates of 20 or 40 1b/A controlled the grass for one season even at the water's edge where it is usually more persistent. At 5 to 10 1b/A, 2,3,5-trichloro-4-pyridinol (pyriclor) controlled reed canarygrass, and it also was effective at 2 1b/A with 2 1b/A of amitrole-T.

The persistence of 4-amino-3,5,6-trichloropicolinic acid (picloram) in soil was measured after varying periods of time up to 3 years with bioassay technique using sunflowers (Helianthus annuus L., var. Advent) as the indicator plant. Rates of application ranged from 0.5 to 48 oz/A on two soil types at Scott, Saskatchewan and two at Lacombe, Alberta. After 1 year, recovery ranged from 20 to 30% of the original application in the 0 to 9-inch depth in each soil not disturbed by tillage directly after application. Recovery of the herbicide applied at rates of 8 oz/A or higher in the fall declined to about 10% after 24 months and to 6% or less after 35 months for even the highest rates. Picloram activity generally was concentrated in the surface 6 inches, indicating limited downward movement due to water in each of the soils. However, there was a tendency toward greater downward movement in the soils having lower organic matter content.

One year after the last of six annual applications of 3-(p-chlorophenyl)-l,l-dimethylurea (monuron) at 2.4, 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron) at 2.4 and 7.2, and 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) at 1.0 and 3.0 lb/A in a furrow-irrigated vineyard on Warden silt loam, a bioassay using oats (Avena sativa L., var. Kanota) as the indicator showed that 1.6, 2.8, 10.6, 0.6, and 2.0 lb/A, respectively, remained in the surface 12 in of soil. Of the total, 62 to 89% was located in the surface 2 in and 86 to 100% was in the surface 4 in. Three years after the last of four annual applications of monuron at 7.2 lb/A, 0.8 lb/A remained in the surface 12 in.

An increase in Ca and SO4 uptake from nutrient solution in juvenile corn (Zea mays L. var. N. J. 9), soybean (Glycine max (L.) Merr., var. Kent) and large crabgrass (Digitaria sanguinalis (L.) Scop.) was obtained with 3-(3,4-dichloroyhenyl)-l-methoxy-l-methyl-urea (linuron) treatment. The uptake of K, Mg, NO3, and PO4 also was followed and varied with the ion and species.

Annual grasses were removed by l,l′-dimethyl-4,4′-bipyridinium salt (paraquat) from subclover (Trifolium subterraneum L.)-Hardinggrass (Phalaris tuberosa L., var. stenoptera (Hack.) Hitchc.) pastures with only temporary damage to these species. If sprayed at the recommended time, total forage production was unchanged and forage quality was improved. Species composition of the pasture was improved by all spraying treatments.

A technique was developed for evaluating the stability of a herbicide suspended in nitrogen solutions of varying molarity. Dispersion stability is expressed as the difference in specific gravity (D value) between a salt solution + herbicide and the salt solution alone using a Westphal balance. The lower the D value, the less herbicide in suspension. Even very low molar solutions significantly lowered the D value. Further, the lower the percent active ingredient in the herbicide the more effectively the surfactants, and possibly other components of the formulated product, offset the adverse effect of salt on dispersion stability.

Barley (Hordeum vulgare L. var. Trail) root growth was inhibited at lower concentrations of 1-(2-methylcyclohexyl)-3-phenylurea (siduron) than was shoot growth. The influence of siduron upon root metabolism was assessed with excised roots grown in 0 or 5 ppm siduron. More glucose-U-14C and leucine-U-14C were degraded to CO2 and less were incorporated into cell wall material and protein by roots grown in siduron. However, roots grown in siduron incorporated more adenine-8-14C into nucleic acids and degraded less adenine to CO2 than roots grown in water. It was suggested that siduron disrupted the normal nucleic acid metabolism of barley roots which was necessary for protein and cell wall synthesis.

Colonial bentgrass (Agrostis tenuis Sibth) and creeping bentgrass (Agrostis palustris Huds) exhibited the most tolerance to 1/2, 1, 1 1/2, and 3 lb/A of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) when grown under cool temperatures, a long photoperiod, and a low pH medium. Injury from treatments was slight to moderate when applied from early to mid-spring, severe when made from late spring to early summer, and very severe when made from late summer to early fall. Silvex appeared to cause the most injury at the 1 and 1 1/2 lb/A rates. Injury was much less from the lower rate of 1/2 lb/A. Root fructosan concentrations decreased with increasing rates under cool temperatures and increased with increasing rates under high temperatures. Bentgrass appeared to tolerate silvex treatments better under low available moisture conditions than under high moisture levels.