In the last few years the possibility of growing small fruits and several vegetable crops without any soil disturbance has been demonstrated. On many soil types crop yield has been unaffected and has sometimes shown a slight increase compared with traditional cultivation. Advantages of non-cultivation include the possibility of increasing crop uniformity and yield by using closer row spacings and completely new methods of crop production, the avoidance of injury to surface-feeding roots, decreased risk of frost and easier mechanical harvesting of some crops. In small-fruit plantations the weed problem has greatly diminished after about 3 years, because of non-disturbance of seeds lying below the germinating zone and the absence of a “seed-bed”. While the surface crust that sometimes forms where the soil is not disturbed may affect plant growth in certain circumstances, no evidence was obtained in recent experiments in Britain that a crust was detrimental to the growth of established plants. However, water infiltration on bare non-cultivated soil was sometimes retarded and increased run-off occurred on sloping sites. Due to the wide diversity of soil types, climatic conditions and crop response it is impossible to generalize about the effect of eliminating cultivation. Nevertheless, as some of the advantages are considerable while the disadvantages can often be overcome it seems likely that non-cultivation practice will extend to many horticultural crops in the future.

Selected, representative research on surfactants, herbicide penetration, and plant cuticles was reviewed briefly. New evidence was presented that surfactants influence the activity of herbicides in oil sprays as spectacularly as in aqueous sprays. Most of the experimental facts about surfactants were integrated in a blanketing theory for entry of herbicides by separate hydrophilic and lipophilic pathways.

The nature and mode of action of surfactants is reviewed. Surfactants are useful additives for formulated herbicides because they contribute to wetting, spreading, emulsification, and solubilization of the herbicide. The use of extra surfactant to increase herbicidal activity is a desirable practice. The factors in selecting a suitable agent are discussed in terms of surfactant properties.

In short-term studies, diquat (6,7-dihydrodipyrido(1,2-a:2’,1′-c) pyrazidiinium salt) and paraquat (1,1′-dimethyl-4,4′-dipyridinium salt) caused a stimulation in respiration and an inhibition in photosynthesis of duckweed (Lemna minor L.). Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and monuron [3-(p-chlorophenyl)-1,1-dimethylurea] caused inhibition of the Hill reaction at rates lower (10-6M) than diquat and paraquat (10-5M), and diquat was considerably more effective than paraquat. The effect of a combination of monuron and diquat on O2 production was additive. Inhibition of the Hill reaction by these dipyridyliums was directly related to their redox potentials. Auto-radiographs of chromatograms and electrochromatograms as well as CO2 studies indicated that neither diquat nor paraquat was degraded in alligatorweed [Alternanthera philoxeriodes (Mart.) Griseb.] and garden, or snap beans (Phaseolus vulgaris L. var. Black Valentine).

Selections of wild oats (Avena fatua. L.) had varying degrees of resistance to isopropyl N-phenylcarbamate (IPC). Strains with gray glabrous lemmas and non-dormant seed tended to be more resistant to IPC than those with brown pubescent lemmas and dormant seed.

Application of 20 to 40 lb/A dichlobenil made prior to emergence accomplished various degrees of control of pondweeds (Potamogeton diversifolius, P. foliosus, P. pectinatus, P. pusillus) and a slender naiad (Najas flexilis). Coontail (Ceratophyllum demersum) was affected only by the higher dosage. Limited control and growth inhibition was achieved on several forms of algae in early spring applications. However, applications made to rooted submersed aquatic plants and filamentous algae (Cladophora, Pithophora and Chara) at postemergence stage of development had little herbicidal effect.

Dichlobenil was not acutely toxic to fish at herbicidal concentrations. The range of median tolerance limits was 10 to 20 ppmw for pumpkinseed (Lepomis gibbosus), bluegill (L. macrochirus), redear sunfish (L. microlophus), and largemouth bass (Micropterus salmoides).

The fate of the C14 label in ethyl N,N-di-n-propylthiolcarbamate (EPTC) was studied following root uptake by alfalfa plants for periods of 2 and 5 days. The uptake and movement of the C14 label in alfalfa was demonstrated by means of autoradiography and measurements of radioactivity with a Geiger-Müller detector. The amount of radioactivity accumulating in plants during the 5-day uptake period was approximately twice the amount accumulating in 2 days. The autoradiographs of plants receiving the 5-day uptake treatment showed an accumulation of C14 in the youngest tissue. Radioactive CO2 was liberated by the treated plants and their extracts contained a large number of C14 labeled compounds.

The effects of thirteen plant growth regulators and herbicides on glucose absorption, metabolism, and incorporation in pea root tissues were studied. Both indoleacetic acid (IAA) and gibberellic acid (GA) caused no effects, while α-naphthalene-acetic acid (α-NAA) and β-naphthaleneacetic acid (β-NAA) caused an increase in catabolic and a decrease in anabolic processes, with the C-1 carbon undergoing the largest change. The absorption of glucose was also inhibited considerably by the synthetic auxins. The carbamates, isopropyl N-phenylcarbamate (IPC), n-Ethyl-N,N-di-n-propylthiolcarbamate (EPTC), and 3-(p-chlorophenyl)-1,1-dimethylurea (monuron) inhibited slightly the glucose absorption. All affected the catabolic process to a certain extent while only IPC caused a change in the anabolic process. Both 2,3,6-trichlorobenzoic acid (TBA) and 2,3,5-triiodobenzoic acid (TIBA) decreased glucose absorption and increased glucose-1-C14 catabolism. TIBA also affected the anabolic process. Other herbicides, 3-amino-1,2,4-triazole (amitrole), maleic hydrazide (MH), 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine), and 2,2-dichloropropionic acid (dalapon) caused varied degrees of inhibition to glucose absorption. Both simazine and dalapon increased C-1 catabolism and exerted no effect on the anabolic process. Only dalapon altered the catabolism of glucose-6-C14. Amitrole and MH decreased the over-all catabolic process with no effect on the pathway; both chemicals increased the anabolic process.

Seeds of winged elm (Ulmus alata Michx.) stored under moist conditions lost viability rapidly. Under dry conditions the seeds lived longer. Winged elm seeds would not germinate at 4 C or 42 C but did at temperatures between these points. Salt concentrations above 20,000 ppm killed the seed; concentrations below this inhibited germination; twelve per cent manitol solutions (16 atmospheres osmotic pressure) prevented germination; pressures lower than this decreasingly affected germination. If the soil moisture level was below 2%, winged elm seeds would not germinate. Removal of the outer husk of the seed did not affect germination. Winged elm seedlings did not emerge if planted at depths below ¼ inch.

Stationary and portable field sampling equipment and techniques are described for the collection of gaseous and aerosol forms of 2,4-D compounds. Air was sampled at the rate of 1 liter per minute through 10 ml of n-decane in a modified midget impinger maintained at approximately 1 C. Field sampling was conducted at two eastern Washington sites for approximately 106 days during the summer of 1963. The presence of isopropyl, butyl, and isooctyl esters of 2,4-D in the atmosphere was established by electron capture gas chromatography. Twenty-four hour average atmospheric concentrations of these esters ranged from undetectable to 3.1 μg/m3.

Seed of common cattail (Typha latifolia L.) germinated 100 percent when the blunt ends of the seed coats were ruptured. Seedlings developed primarily while submersed in water. Growth of the seedlings was rapid. A single plant in 6 months developed a network of rhizomes covering an area 10 feet in diameter. Pistil-late spikes 7 inches long produced an average of over 222,000 seeds.

Greenhouse experiments showed that monuron, 3-(p-chlorophenyl)-1,1-dimethylurea, uniformly applied to the soil surface immediately after planting, was about twice as toxic to seedling cotton as was diuron, 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Phytotoxicity was increased when either of these herbicides was applied with either of the systemic insecticides phorate, O,O-diethyl S-(ethylthio) methyl phosphorodithioate or Di-syston, O,O,-diethyl S-[2-(ethylthio) ethyl] phosphorodithioate.

All horizontal underground structures were roots and not rhizomes. The small, light-colored feeder roots are short-lived and consist mainly of primary tissue. Only one transition zone per clone was found. This was found in the collet (lower hypocotylary swelling). The transition from exarch, radial stele of the root, to endarch, collateral stele of the upper collet, was complete in approximately 2500 microns. All root primordia examined had endogenous origin from pericycle and pericyclic tissues. Buds arose endogenously in roots but exogenously in the region of the hypocotyl with endarch protoxylem. Primordia were often identified as roots or shoots prior to their emergence from the main axis.

The most promising of 13 herbicides for the control of southern naiad (Najas guadalupensis (Spreng.) Magnus) were acrylaldehyde (acrolein), mono-N,N-dimethylcocoamine and di-N,N-dimethylcocoamine salts of 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid (endothall), 6,7-dihydrodipyrido[1,2-a:2’,1′-c] pyrazidiinium salt (diquat), and 1,1′-dimethyl-4,4′-bypyridinium salt (paraquat). Acrolein and the 2 alkylamine salts of endothall gave the most rapid kill of southern naiad but retreatment was necessary at the end of 16 weeks. Diquat and paraquat were the 2 most promising materials evaluated. Large scale applications of acrolein, di-N,N-dimethylcocoamine salt of endothall and diquat confirmed these results. Diquat and paraquat were the only herbicides of the 13 that were not toxic to fish.

Saltcedar (Tamarix pentandra Pall.) and Woods rose (Rosa woodsii Lindl. var. ultramontana [Wats.] Jeps.) were sprayed with systemic herbicides at frequent intervals over a 2-year period. Root samples were collected at each spray date and analyzed for “total available carbohydrates.” Food reserve levels in the roots and response to herbicides were not correlated.

Plants of Zebrina pendula L., Phaseolus vulgaris L., Sorghum halepense (L.) Pers., and Chenopodium album L. were sprayed with a solution containing herbicide (sodium 2,4-dichlorophenoxyacetic acid or sodium 2,2-dichloropropionic acid), surfactant (sodium dioctylsulfosuccinate), and fluorescent tracer (sodium pyrenetrisulfonate). In most instances plants having stomata relatively open absorbed more tracer (based on UV observation) and more herbicide (based on injury and growth responses) than those with stomata relatively closed. Differences, however, were less than those expected from studies using detached leaves, probably from poorer control of stomatal aperture in intact leaves. There was good agreement between degree of opening and tracer uptake.

Monuron [3-(p-chlorophenyl)-1,1-dimethylurea] and neburon [1-n-butyl-3-(3,4-dichlorophenyl)-1-methylurea] were applied to a sandy loam soil which was planted to several crops in southern California. Monuron at 2, 4, and 8 lb/A and neburon at 2 lb/A were below phytotoxic levels by 12 months. Neburon at 4 lb/A persisted at phytotoxic levels for over 16 months, and at 8 lb/A for over 24 months.

When weeds were controlled in sorghum by hand-weeding or a herbicide there was no advantage or need for cultivation. Control of weeds in sorghum with preemergence herbicides was feasible, but the combination of cultivation and herbicides gave more dependable weed control than either method used alone. Preemergence applications of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) were the most effective for controlling weeds and increasing sorghum yields. In decreasing order of effectiveness were 2-chloro-4,6-bis(isopropylamino)-s-triazine (propazine), 2-chloro-N,N-diallylacetamide (CDAA) + trichlorobenzyl chloride (TCBC), and postemergence atrazine applications.

The ribonucleic acid (RNA) content of corn roots and etiolated coleoptiles treated with amitrole (3-amino-1,2,4-triazole) was very similar to that in untreated tissues. Amitrole consistently decreased the acid-soluble nucleotide content of etiolated corn coleoptiles.

The minimum red-light (> 590 mμ.) intensities from fluorescent tubes at which growth or maintenance of original fresh weight were obtained at 20 C in a growth chamber for 28 days were 11–20 foot-candles for waterstargrass (Heteranthera dubia [Jacq.] Mac M.) and 12–45 foot-candles for coontail (Ceratophyllum demersum L.). Duckweed (Lemna minor L.) frond number increased significantly at 45 foot-candles red light, and the fresh weight probably increased at 45 foot-candles. The intensites of 11–45 foot-candles constituted 1.0–3.8 percent of the red portion of full sunlight.