No abstract

Salt injury to grasses and legumes in roadside seedings is becoming an increasingly serious problem in areas where deicing salt is used during winter months. This paper reports on results of three greenhouse trials conducted to evaluate salt tolerance among 40 grass and legume species, cultivars, and genotypes. A 2.65 M sodium chloride (NaCl) solution was added weekly for up to 5 weeks to pots of seedling plants in a Derinda silty clay loam (fine, mixed, mesic Typic Hapludalfs). Salt tolerance was measured by comparing dry matter (DM) yields of salt and no‐salt treatments and by visually scoring foliage injury. In the final trial, which involved a rescreening of the most salt tolerant species from all previous trials, 14 of the 15 entries had salt treatment DM yields which were not significantly different from no‐salt treatment yields, and five also had salt treatment foliage injury scores which were not significantly different from those of the no‐salt treatment. These five were: lemmon alkaligrass [Puccinellia lemmoni (Vasey) Scribn.]; alkali sacaton [Sporobolus airoides (Torr.) Torr.]; nuttall alkaligrass [Puccinellia airoides (Nutt.) Wats. and Coult.]; a Puccinellia roadside selection, and weeping alkaligrass [Puccinellia distans (L.) Parl.]. Entries which had no significant DM yield reduction but showed serious foliage injury were: creeping bentgrass [Agrostis stolonifera L., var. palustris (Huds.) Farw.] cv. Seaside; quackgrass [Agropyron repens (L.) Beauv.]; tall fescue (Festuca arundinacea Schreb.) cv. Alta; perennial ryegrass (Lolium perenne L.) common and cv. NK 200, creeping meadow foxtail (Alopecurus arundinaceus Poir.) cv. Garrison; redtop (Agrostis alba L.); creeping red fescue (Festuca rubra) cv. Ruby; and rough stalk bluegrass (Poa trivialis L.). Among legumes tested, alfalfa (Medicago sativa L.) cv. Vernal and sainfoin (Onobrychis viciaefolia Scop.) cv. Eski were the most salt tolerant, but both ranked lower than the better grasses. Six Kentucky bluegrass (Poa pratensis L.) cultivars were among those entries which had the greatest dry matter yield reductions and the most severe foliage injury when treated with salt.

While simazine [2‐chloro‐4,5‐bis(ethylamine)‐s‐triazine] has been used for several years to control perennial broadleaf weeds in alfalfa (Medicago sativa L.), it occasionally fails to provide adequate weed control, or causes crop injury. Other triazine herbicides have been shown to provide more reliable weed control but also may injure the crop. Consequently, this study was conducted to determine which triazine herbicide was least injurious to alfalfa and if alfalfa cultivars differed in their susceptibilities to the herbicides. Included in the study were five alfalfa cultivars and the herbicides atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], cyanazine [2‐chloro‐4‐ (1‐cyano‐1‐methylethylamino)‐6‐ethylamino‐s‐triazine], secbumeton (2‐sec‐butylamino‐4‐ethylamino‐6‐methxy‐s‐triazine) and simazine. The cultivars were established on silt loam (Typic Argin‐doll Fine‐Silty Mixed Mesic) and loamy sand (Typic Udipsament Sandy‐Mixed) soils. Results of tests conducted on both soils indicated that the ‘Vernal,’ ‘Saranac,’ and ‘Iroquois’ cultivars had the greatest yield potential under Wisconsin conditions, but when expressed as a percentage of yield in untreated plots, the ‘Tempo’ cultivar was injured least by the herbicides. The ‘DuPuits’ cultivar, while initially responding to the triazine herbicides much like the other cultivars, exhibited greater injury after overwintering. Initial injury to the Vernal cultivar on the silt loam soil was greatest from atrazine, secbumeton, and cyanazine, but recovery was nearly complete by the spring following treatment. On the loamy sand soil, however, atrazine and high rates of simazine produced the greatest initial injury, and injury to the Vernal cultivar persisted through the following spring.

High starch samples are difficult to filter using the neutral detergent fiber (NDF) method. Additional research is also required to identify the best in vitro dry matter disappearance (IVDMD) technique for prediction of in vivo digestibility of whole‐plant corn (Zea mays L.) forage. We designed experiments to compare methods of NDF and IVDMD determination for predicting in vivo intake and digestibility, respectively. In Experiment I, normal corn (105‐day maturity) harvested at five maturity stages (75% silk and 12, 24, 36, and 48 days later) was analyzed for NDF with and without amylase addition during refluxing. The standard deviation among triplicate samples was ±1.08 and ±0.56 for the unmodified and modified procedures, respectively. In Experiment II, normal and brown midrib corn of three maturity stages (75% silk and 24 and 60 days later) and mature (60 days) waxy and male sterile corn were analyzed using the treatments outlined above. In vivo digestibility was regressed on IVDMD dtermined by four methods (IVDMD, IVDMD + amylase, IVDMD + nitrogen, and IVDMD + NDF) and in vivo intake on NDF and NDF + amylase values. A greater percentage of variation in in vivo dry matter intake was explained when amylase was added (R2 = 96.0%) than when not (R2 = 52.0%). The addition of amylase to the in vitro fermentation vessel improved the prediction of in vivo dry matter digestibility (R3 = 67.2%) compared with the unmodified procedure (R2 = 53.3%).