Mapping Out Cotton Growth Can Avoid Disappointment at Harvest Time in the Fall

Drive around the cotton fields in the Valley and you will notice each field looks a little different.

In some fields, the plants may have eight fruiting branches. In others, the plants may be seem smaller with fewer fruiting branches.

Yes, every cotton field develops at a different rate. Field scout Damien Jelen sees it every day ashe visits fields throughout the region.

For cotton growers, charting the progress of their plants is an important practice that can make a difference in yield and profit.

Cotton experts encourage growers to do plant mapping, which serves a guide for evaluating the crop’s health during the season.

Charting cotton plant's development can improve yield.

Taking regular measurements and comparing them to growth guidelines will let growers know how the crop stands – whether it is doing well or under stress because of pests, diseases or lack of water. By knowing the status, growers can take proactive steps to add fertilizer or plant growth regulators, when to time pesticide or herbicide applications, manage irrigation and identify fruiting problems.

At the moment, plants are around their 12th and 13th nodes, according to Damien.  The first bloom has occurred in many fields. “The plants are about three feet tall,” he says. 

Plant monitoring during early squaring lets growers assess plant vigor and square retention. They should measure for plant height, the number of main stem nodes and the first position squares on the terminal five fruiting branches. Generally, a square retention rate of 80 percent or higher is ideal for going into bloom.

If retention drops, growers might opt to use growth regulators to enhance development. They should check with their pest control advisor or local University of California farm advisor before making any application.

Here’s one simple method to follow. The cotton season can be divided into four management periods:

·         From plant emergence to square: This is when you count plant stand and height and the number of nodes. Walk around the field and check for drainage issues, missing rows and pest damage. This information will help with replanting and pest management decisions.

·         From firstsquare to first bloom: In this stage, sample at least five plants in four different sections of the field. Then collect information about plant height, the number of nodes, fruiting branches and square retention. Also record fruit set and growth. This information is important for crunching numbers and guiding decisions on pest control and the possible use of growth regulators. For example, square retention calculations can assist in developing pest management strategies.

·         From first bloom to cut-out: This is the time when the plant becomes larger. You record plant height, number of nodes, nodes above first position white flower and first position squares above the white flower and first position bolls below white flower in the first or second position. This information indicates how the crop is developing and provides insights about vegetative growth and boll development as you approach cut-out – the final stage of plant growth before the bolls open.

·         From Cut-out to defoliation:Measure the plants for boll retention, boll regrowth and boll opening. Noting nodes above cracked boll will help with the decision about the timing of defoliation.

UC IPM offers a wealth of information and tools for cotton growersthe sitemonitoring cotton plant growth.

FIELD DAYS: A trio of University of California extension and farm advisors willoffer tips and provide the latest developments in cotton across in the San Joaquin Valley during a field day tomorrow in Mendota. Open to all growers and pest control advisors, the free event starts at 9:30a.m. atPik-A-Lok Farms on Bass Avenue in Mendota. Featured speakers are:Dan Munk, UCCE Fresno County farm advisor and cotton specialist, who will discuss monitoring cotton for improved yield performance. Bob Hutmacher, UCCE extension specialist of the Westside Research and Extension Center, who will provide an update cotton diseases and plant development issues. Jeff Mitchell, associate vegetable crop specialist at the Kearney Ag Center, will talk about going beyond the hype of soil health and doing someth

ing about it.

On Tuesday, July 31: UC extension advisors and a county official will update farmers about the latest trends in alfalfa field and pest management and pesticide regulations during a field day in Firebaugh. The event will be from 10 a.m. to 12:30 p.m. at the Firebaugh-Mendota United Methodist Church, 1660 O Street, Firebaugh. Featured speakers are:

·         Lynn M. Sosnoskie, agronomy and weed science advisor, for the University of California Cooperative Extension in Merced and Madera counties, who will discuss weed control in alfalfa and the chemical, cultural and biological factors that can affect success and failure.

·         Tom Casey, pest control operations official for the Fresno County Agricultural Commissioner’s Office, who will cover current pesticide use and regulations.

·         Nicolas Clark, agronomy and nutrient management advisor at UCCE Kings, Tulare and Fresno counties, who will offer tips about insect pest management in San Joaquin Valley alfalfa hay.

Continuing education credits have been approved and include one hour of regulations. The two field days are sponsored by the San Joaquin Sustainable Farming Project, which provides farmers with valuable strategies to improve yields while becoming better environmental stewards in today’s challenging economic and regulatory climate. For more information about the field days, contact Project Director Marcia Gibbs at (530) 370-5325.