Reproduction of muskellunge Esox masquinongy has failed in many waters that formerly supported self‐sustaining populations. Laboratory experiments were conducted to isolate causes of such failures. Differential mortality occurred among lots of muskellunge eggs incubated in jars of unaceated lake water over substrates of sand, gravel, silt, aquatic macrophytes, wood, tree leaves, polyethylene screen, and bare glass. High and rapid early mortality (days 1–2), attributable to low dissolved oxygen (DO) concentrations (0–0.1 mg/liter), occurred among eggs incubated on leaves and macrophytes. After day 3, Saprolegnia sp. fungus was implicated in high egg mortalities in jars with inorganic substrates and moderate DO concentrations (3.8–4.1 mg/liter). Lowest mortality rates occurred on organic substrates (silt and wood) amidst intermediate DO concentrations (0.4–1.7 mg/liter) and limited fungal infestation. Among eight midwestern lakes and reservoirs, measured DO at the substrate‐water interface in four of them was high (means, 6.0–8.4 mg/liter) and showed little microstratification; these lakes contain self‐sustaining muskellunge populations. The other four lakes showed extreme DO microstratification and virtual anoxia (means, 0.4–2.4 mg/liter) at the substrate‐water interface; muskellunge populations in these lakes are supported almost wholly by stocking. Suitable spawning substrates in these lakes are aerated by annual reservoir drawdown, have inherently low biological oxygen demand, or support dense beds of stonewort Chara sp. Reproductive failure is associated with spawning areas having deep accumulations of organic matter and dense macrophyte growth. Improvements of spawning habitat to prevent or alleviate hypoxia are among the options available to manage this species.

Response of electronic, printed-circuit wetness sensors was compared to visual observations of free water on processing-tomato leaflets during 13 dew-onset and 11 dew-dryoff events. Deployment angle and painting of the sensor surface significantly (P < 0.01) influenced the mean absolute time difference between observation of the first wet or dry leaflet at the top of the tomato canopy and the start of sensor response (kΩ) to dew onset or dryoff, respectively. Compass orientation of painted sensors deployed at 45° to horizontal had no significant effect on response to dew onset or dryoff. For sensors deployed at 45° during dew onset, mean absolute time difference between the first observed wet leaflet and the start of unpainted sensor response was 4.00 h, compared to 0.58 and 1.09 h for sensors with three and nine coats of paint, respectively. At deployment angles of 30 or 0°, paint coating had a lesser influence on time differences between visual observation and sensor response to dew onset. During dew dryoff, absolute time differences between visual confirmation of the first dry leaflet and the start of sensor response were ≤1.03 h for all sensors. Trends were similar when the visual observation criterion was 50% wet or dry leaflets during dew onset or dryoff, respectively, rather than first wet or dry leaflet. Standard deviation of sensor response during dew onset was generally larger for unpainted sensors than for sensors with three coats of paint, especially when deployed at a 45° angle. The apparent temperature of unpainted sensors at 0 or 30° deployment angles decreased much more rapidly during the period preceding dew onset than for painted sensors at the same deployment angles, whose apparent temperatures cooled at rates similar to those of tomato leaflets positioned at these angles. The results indicate that deployment angle can significantly affect accuracy and precision of dew-duration measurements by unpainted, but not painted, electronic wetness sensors.

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Plastic composite supports containing 50% agricultural products (oat hulls, soybean hulls, yeast extract, soybean flour, dried bovine erythrocytes, bovine albumin, and/or mineral salts) and 50% (wt/wt) polypropylene were produced by high-temperature twin-screw extrusion. The research employed two half sets of a fivefactorial fractional design (2 5 ؊ 1) to evaluate the effects of different agricultural components on the properties of the plastic composite supports and to select the best plastic composite support formulation for lactic acid fermentation. The biofilm population was affected by the contact angle and relative hydrophobicity of the supports (r ‫؍‬ 0.79 to 0.82). Lactic acid was produced by the suspended cells (r ‫؍‬ 0.96) and the biofilm on the plastic composite support discs (r ‫؍‬ 0.85). Incorporation of yeast extract into plastic composite supports enhanced growth of free and attached cells in minimal medium (P < 0.0001). The presence of soybean hulls, yeast extract, or mineral salts in plastic composite supports produced less hydrophobic supports (P < 0.0001) and enhanced cell attachment (P < 0.03). Under all conditions, suspended-cell and polypropylene disc controls gave negligible lactic acid production and cell density. Plastic composite supports containing soybean hulls, yeast extract, soybean flour, bovine albumin, and mineral salts gave the highest biofilm population (2.3 ؋ 10 9 CFU/g of support), cell density (absorbance of 1.8 at 620 nm), and lactic acid concentration (7.6 g/liter) in minimal medium.