Computer Management
of California Rice - 93



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Project Leader and Principal UC Investigators


DickPlant.jpg (13895 bytes)After several years of fine-tuning, a computer software program to guide growers through their decision-making process before, during and after the season is now available. The University of California's Integrated Pest Management Project began distributing CALEX/Rice to farmers and pest control advisers in early 1994. This "expert system" integrates the problem-solving knowledge of experts in many fields of crop production. This new tool will give growers with personal computers the ability to evaluate the outcomes of different management scenarios through simulation and can address several, often competing factors.

The framework for the program is called CALEX, developed by the IPM program for use in production of many crops, most notably cotton. The customized finish work for CALEX/ Rice was developed by UC scientists working in close collaboration with a group of rice growers. The heart of the program consists of pest management sections for weeds, seedling pests and invertebrates, and agronomic management modules for variety selection, stage of rice development, nitrogen fertility, potassium, phosphorous and zinc fertility, harvesting and water use. Some of the features of each module are described below.

  • Weeds - Descriptions and control recommendations of major weed species. Effectiveness of different herbicides. Details of how varying field conditions and crop status can restrict herbicide use.
  • Seedling pests - Guidelines for systematic sampling. Symptoms and descriptions of pests such as crayfish, tadpole shrimp and rice water weevil. Alternative actions depending on pest density, seedling status and economic threshold.
  • Invertebrates - Season-long guide for sampling, symptoms and recommendations for rice water weevil, tadpole shrimp, rice seed midges, armyworms and crayfish.
  • Variety selection - Field locations and climatic conditions are matched to 14 of the most commonly grown commercial cultivars. Planting dates, varietal characteristics such as grain type, maturity, vigor and stem rot resistance are also included.
  • Rice development - A degree days model is used to predict when each cultivar will reach the following growth stages: mid-tillering, maximum filtering, panicle initiation, flag leaf, 50 percent heading and grain maturity.
  • Nitrogen fertility - Preplant recommendations based on previous crop and residue management, tillage, fertilizer method, type and source (including green manure) to achieve maximum yield. Leaf nitrogen analysis and herbicide considerations used for in-season recommendations.
  • P, K and Zn fertility - Preplant recommendations based on soil analysis; in-season recommendations based on leaf tissue analysis. Considered separately from nitrogen fertilization for ease of use.
  • Harvesting - Predicts cultivar-specific harvest date by determining when grain moisture content of standing rice reaches optimum value for maximum head rice recovery. Includes an "energy balance model" to adjust for cultivars grown in specific areas.
  • Water use - Daily crop water use is computed from the product of daily crop coefficient and the daily crop coefficient and the daily reference evapotranspiration. Crop coefficient takes into account developmental stages of different varieties

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