Yellow and purple nutsedge are problem perennials that resist common control measures. High temperatures, irrigation, and relatively non-competitive crops combine to greatly increase the severity of nutsedge infestations in the Southwest. We compared the growth and susceptibility of purple and yellow nutsedge to chemical and cultural control measures at several locations in southern California. When not controlled, low initial populations of either species led to heavy infestations later in the season. Purple nutsedge was far more prolific in both tuber production and above-ground growth. Summer rotations that included crops with dense canopies severly decreased nutsedge shoot and tuber growth. Cool-season crops planted into heavy nutsedge infestations in the fall are generally unaffected because nutsedge infestations in the fall are generally unaffected because nutsedge soon enters dormancy and ceases growth. Solarization, or pasteurization of the upper soil layers, was effective in decreasing tuber formation. Tillage effectively spread local infestations over larger areas.
Milton E. McGiffen Jr., David W. Cudney, Edmond J. Obguchiekwe, Aziz Baameur, and Robert L. Kallenbach
Milton E. McGiffen Jr., John Manthey, Aziz Baameur, Robert L. Greene, Benjamin A. Faber, A. James Downer, and Jose Aguiar
A 1992 article by Nonomura and Benson (Proc. Natl. Acad. Sci. 89:9794-979X) reported increased yield and drought tolerance in a wide range of C3 species following foliar applications of methanol. The article was widely reported in the trade and popular press, which created a huge grower demand for information on the use and efficacy of methanol. To test the validity of the reports, we applied methanol with and without nutrients to a wide range of crops across California following Nonomura and Benson's (1992) protocol. Crops included watermelon, creeping bentgrass, lemons, savoy cabbage, carrots, romaine lettuce, radish, wheat, corn and peas. Environments included the greenhouse and field tests in coastal, inland valley, and desert locations. To test whether methanol improved drought tolerance, the savoy cabbage and watermelon experiments included both reduced and full irrigation. In no case was yield increased or drought tolerance attributable to methanol treatment. In some cases, methanol caused significant injury and decreased yield.
Milton E. McGiffen Jr., Robert L. Green, John A. Manthey, Ben A. Faber, A. James Downer, Nicholas J. Sakovich, and Jose Aguiar
To test the usefulness of methanol treatments in enhancing yield and drought tolerance, we applied methanol with and without nutrients to a wide range of crops across California: lemon (Citrus limon L.), creeping bentgrass (Agrotis palustris Huds.), romaine lettuce (Lactuca sativa L.), carrot (Daucus carota L.), corn (Zea mays L.), wheat (Triticum aestivum L.), pea (Pisum sativum L.), and radish (Raphanus sativus L.). Environments included greenhouse and field tests in coastal, inland-valley, and desert locations. Methanol did not increase the yield or growth of any crop. In some cases, methanol caused significant injury and decreased yield.
Jaime Barros da Silva Filho, Paulo Cezar Rezende Fontes, Paulo Roberto Cecon, Jorge F.S. Ferreira, Milton E. McGiffen Jr., and Jonathan F. Montgomery
Potato seed production by conventional methods represents a sizeable investment that, when passed on to farmers, can decrease their profit margins. Potato minitubers produced by aeroponic systems are space- and cost-efficient, and they also provide healthy propagules to be used by farmers. We evaluated the effects of different misting nozzle types, with and without an antidrip feature, and spray direction on potato minituber yield using the Federal University of Viçosa (UFV) Aeroponic System. Potato plants (cv. Agata) propagated from sprouts were grown in a covered, high-density 100-L polyethylene bucket. The experiment was set up in a randomized complete block design with four replicates and eight treatments combining misting nozzle types (Fogger, MA-30, and CoolNet) with and without antidrip and comparing upward with downward spray directions. Plants were evaluated weekly from 33 to 68 days after transplant (DAT). The parameters used to evaluate treatments were number and mass of minitubers as a function of harvest times, dry mass of roots, stems, leaves, and total biomass. The number and fresh weight of minitubers, as well as root dry weight, stems, leaves, and total biomass were affected by misting nozzle types and spray direction. Treatments also affected biomass partitioning of roots, stem biomass, and the shoot:root ratio. There was also an effect of harvest time on the number and fresh weight of minitubers for various combinations of misting nozzle type and spray direction, except for minituber number with the CoolNet misting nozzle without antidrip and downward spray direction. On the basis of the assessed parameters, the best minituber production system was achieved with the Fogger spray combined with no antidrip, a rate of 12 L·h−1, and with the downward spray direction. The UFV Aeroponic System produced an average of 491 minitubers per plant. This system is simple to implement and may lead to a more affordable upscaling of potato seed minituber production.