Invinsa blocks ethylene perception by plants and can reduce the negative effects of water stress on crop growth. The objective of this study is to measure the effect on corn growth and yield of Invinsa application at incipient water stress. A study was conducted at the University of Arizona Maricopa Agricultural Center where Invinsa was applied on 15 June and 20 June in blocks with adequate irrigation or deficit irrigation, which received no irrigation water for 10 days past incipient stress beginning on 15 June. Invinsa had inconsistent effects on corn growth and yield. The most notable effect of Invinsa, however, was an increase in total plant yield from 11.09 to13.43 t/a measured on 23 July and from 11.36 to 13.61 t/a measured on 13 Aug in the adequate irrigation block for Invinsa application on 15 June. However, Invinsa had no effect on final grain yield. The lack of a consistent response to Invinsa may be explained by the higher than optimum temperature at time of application or other unknown factors.

Information on silage corn yield and quality can help silage growers and users choose varieties that best fit their needs and area. We conducted a silage corn variety trial using seven varieties for use in Central Arizona. Variety 28Z47 produced the higher silage yield with an average of 30.4 ton/acre and the variety 28V71 had the highest crude protein content (8.13%) among the eight. Varieties that produced higher yield, higher crude protein, and lower NDF than the average of the eight varieties were 851VT3 and TMF-2L-872.

The Crop Water Stress Index (CWSI) was used to schedule irrigations on Jubilee sweet corn on 12 drip- irrigated plots at the Campus Agricultural Center in Tucson. Irrigations were to be scheduled at 0.15, 0.35, and 0.50 CWSI values to represent a wet, medium and a dry treatment. Actual average CWSI values at time of irrigation were for 0.14, 0.36, and 0.48. There were no significant yield or quality differences for the wet and medium treatments with exception of a greater ear diameter in the wet treatment. Yield and quality significantly decreased for the dry treatment scheduled at a CWSI value of 0.48. Irrigation application totals were 26.4, 24.2 and 18.3 inches for the wet, medium and dry treatments respectively.

No observable injury was evident by any herbicide treatment on any of the twelve sweet corn varieties during the season. Overall, pendimethalin (Prowl®) treatments applied preemergence (PREE) provided very good control ( >87 %) of all weeds rated. Metolachlor (Dual®), EPTC plus safener (Eradicane®), dimethanamid (Frontier®), and cyanazine ( Bladex®) treatments gave good control ( >80 %) of pigweeds ( Amaranthus sp.) and purslane (Portulaca oleraceq) with annual yellow sweetclover (Melilotus ocf`icinalis) not adequately controlled. All treatments except Bladex alone gave good control of volunteer sudangrass.

A field experiment was conducted at the Maricopa Agricultural Center on a Casa Grande sandy loam soil to compare the nitrogen (N) utilization efficiency achieved using slowrelease and conventional nitrogen fertilizers under subsurface drip irrigated melon production conditions. 'Mirage' watermelon, 'Laguna' cantaloupe and 'Gallicum' honeyloupe were used as the test crops. Single, preplant applications of three slow - release products (methylene urea, coated ammonium sulfate and coated urea) were compared with the use of urea -ammonium nitrate added in either one or three split applications. The total amount of N applied to all treated plots was 100 lbs. per acre. Whole plant samples were taken four times during the season to determine N uptake patterns. Petioles from the youngest fully expanded leaves were sampled on four dates throughout the season to monitor the N status of all plots. At harvest, total and marketable melon yields were determined. In general, the methylene urea treatment was superior to the use of coated (NH₄)₂SO₄ which in turn was far superior to the coated urea product. The split UAN and preplant UAN treatments had the highest numerical values for total N uptake for all three melon types. However, these values were usually not statistically different from the N uptake in response to the three slow- release N treatments. The type of water delivery system may have reduced the potential advantages of using slow-versus fast-release N fertilizers.

Preplant incorporated and/or preemergence herbicide treatments including metolachlor (Dual®), EPTC with safener (Eradicane®), cyanazine (Bladex®), pendimethalin (Prowl®), and tank-mix combinations provided good (88 %) to excellent ( >98 %) weed control of prostrate and tumble pigweeds and purslane in sweet corn.

The sequence of preemergence (PREE) herbicide metolachlor (Dual II®) followed by postemergence (POST) herbicide mixture of primisulfuron plus prosulfuron (Exceed®) provided season-long near complete weed control in sweet corn. Preplant incorporated (PPI) treatments of dimethenamid (Frontier®), EPTC plus safener (Eradicane®), and herbicide mixture FOE 5043 plus metribuzin (Axiom®, Bayer) provided effective weed control for most of the season. Similar effective weed control was observed for PREE treatments of pendimethalin (Prowl®), Frontier, and Axiom.

Season-long near complete weed control in sweet corn was achieved with preemergence (PREE) herbicide applications of pendimethalin (Prowl®), metolachlor (Dual®), or thiafluamide/metribuzin (Axiom®) followed by postemergence applications of bentazon (Basagran®) or dicamba (Banvel®). Basagran applied alone POST gave very good control ( >93 %) of lambsquarters (Chenopodium album) and purslane (Portulaca oleracea) but did not adequately control tumble pigweed (Amaranthus albus). Prowl applied alone PREE gave acceptable control of most weeds. POST applications of prosulfuron/primisulfuron (Exceed®) caused moderate corn injury by shortening internodes and overall plant height and slight foliar chlorosis.

Invinsa blocks ethylene perception by plants and can reduce the negative effects of water stress on crop growth. The objective of this study is to measure the effect on corn growth and yield of Invinsa application at incipient water stress. A study was conducted at the University of Arizona Maricopa Agricultural Center where Invinsa was applied on 15 May in blocks with adequate or deficit irrigation. The deficit irrigation block received no irrigation water for 7 days past incipient stress beginning on 15 May, but otherwise received adequate water during the other parts of the season. Invinsa had little or no effect on crop growth measured at five different dates during the growing season. Invinsa had no effect on grain yield, grain moisture content, harvest index, ear number, kernels per ear, kernel weight, and silking date. We were not able to measure an effect of Invinsa on photosynthetic rate, conductance to water, intercellular CO2 concentration, vapor pressure deficit, or leaf temperature. However, Invinsa increased daily water use at various time periods, particularly in the adequate irrigation regime. The lack of a response this year to Invinsa, other than water use, is similar to the results from last year where no consistent response was measured. Invinsa has increased corn yield in other regions, and heat and/or water stress at the Maricopa may mask the effects of Invinsa or render it ineffective.

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