Synopsis Turf grown on low N was more resistant to high temperatures than that on high N. Neither P nor K affected this resistance. High levels of N and P gave less‐resistant plants than high N and low P. The reverse was true with N and K.

‘Washington’ Creeping Bentgrass turf (Agrostis palustris Huds.) clipped at 0.635 cm (1/4 inch) was fertilized with seven nitrogen sources applied at two rates over a 5‐year period. Differences in nitrogen response were noted and correlated with fresh and dry weight yields, with percentage dry weight, and with mineral analysis of leaf tissue. Activated sewage sludge, inorganic nitrogen sources, and urea produced similar growth responses. Processed tankage and ureaformaldehyde were less effective in promoting growth than other nitrogen fertilizers.

Landscape situations frequently are such that trees may be well established when an attempt is made to establish turf. This occurs when renovating an old lawn, changing type of turf, or where new subdivisions are located in areas of established trees. This study was initiated to assess the effects of established silver maple (Acer saccharinum) and honey‐locust (Gleditsia triacanthos L.) roots on newly seeded Kentucky bluegrass (Poa pratensis). A connecting pot technique was used to maintain nearly uniform light intensity over tree‐shaded pots with or without tree roots. Silver maple and honeylocust roots established prior to seeding of common Kentucky bluegrass had a highly significant effect on growth of bluegrass, but the bluegrass had no significant effect on tree roots. Dry weight of foliage, sod and root yields, and root/sod ratios were reduced by presence of tree roots. Penetration of bluegrass roots into the main soil mass was restricted by silver maple roots. A mat of bluegrass roots about 0.95 cm (⅜ inch) thick was easily lifted from the soil containing tree roots. Established tree roots reduced the number of bluegrass plants established from seed, but had no effect on tiller production. It is hypothesized that biochemical inhibition (allelopathy) may be involved.

Synopsis An evaluation of the effects of 3 types of solution‐modifying agents‐evaporation‐retardant, surfactant, and osmotic agent‐on the growth of Kentucky bluegrass in nutrient solutions was made. Variations in osmotic pressure and surface tension of nutrient solutions affected turfgrass production. Increasing osmotic pressure decreased growth of foliage and increased root development. Decreasing surface tension decreased growth of foliage. An evapo‐retardant added to nutrient solutions had little effect on either osmotic pressure or surface tension but increased yields of foliage.

Synopsis Merion bluegrass grown in solution culture produced lower yields of foliage under low levels of nitrogen and high levels of osmotic pressure than when treated with high nitrogen and low osmotic pressures. Turf was resistant to inoculation with Puccinia graminis Pers. at all treatment combinations. Numbers of Helminthosporium sativum Pammel, King, and Bakke lesions per leaf blade and average size of lesions increased with increasing levels of nitrogen and decreasing osmotic pressure.