Water-Seeded Rice: Using Water to Control Weeds in Organic Production

Originally published March 26, 2024. Updated November 2026 with additional information on water management and organic weed control from Lundberg Family Farms.

Dr. Ronnie Levy, Retired Extension Rice Specialist at LSU wrote this article for the April 2022 issue of Rice Farming Magazine. I clipped it out and thought, “this will come in handy someday!”¹ I am putting this out there again because our organic rice producers are facing some real problems with weeds in rice including weedy rice, hemp sesbania, jointvetch and certainly weedy grasses.

In 2023, I was at Joe Broussard’s farm near Nome, looking at a rice field that was headed out and looking great. On the other side of the levy was a field choked with weeds – what was the difference? One was water-seeded rice, and the other was not. Joe had used water seeding and his flood to control weeds “the old-fashioned way!” So, read this article by Dr. Levy and think about it……

“Most rice is drill-seeded in Louisiana — about 80% — but there is a renewed interest in water-seeding rice for weedy rice suppression (or many other weeds in organic systems).” Rice Farming, April 2022. Dr. Ron Levy.

The most common water-seeding method in Louisiana is the pinpoint flood system. After seeding, the field is drained briefly. The initial drain period is only long enough to allow the radicle to penetrate the soil (peg down) and anchor the seedling. A three- to five-day drain period is sufficient under normal conditions.

The field then is permanently flooded until rice nears maturity (an exception is midseason drainage to alleviate straighthead (physiological problem of rice) under certain conditions).

In this system, rice seedlings emerge through the floodwater. Seedlings must be above the water surface by at least the 3 to 4-leaf rice stage. Before this stage, seedlings normally have sufficient stored food and available oxygen to survive. Atmospheric oxygen and other gases are then necessary for the plant to grow and develop.

The pinpoint flood system is an excellent means of suppressing weedy rice emerging from seeds in the soil because oxygen necessary for weedy rice germination is not available as long as the field is maintained in a flooded (or saturated) condition. A continuous flood system, another water-seed system, is limited in Louisiana. Although similar to the pinpoint flood system, the field is never drained after seeding.

Regarding the water-seeded systems, a continuous flood system is normally best for red rice suppression, but rice stand establishment is most difficult. Even the most vigorous variety may have problems becoming established under this system. Inadequate stand establishment is a common problem in both systems.

Fertilization timing is the same for both the pinpoint and continuous flood systems. Phosphorus (P), potassium (K), sulfur (S) and zinc (Zn) fertilizers are applied preplant incorporated as in the dry-seeded system. Once the field is flooded, the soil should not be allowed to dry.

If the nitrogen requirement of a particular field is known, all nitrogen fertilizer can be incorporated prior to flooding and seeding or applied during the brief drain period in a pinpoint flood system. Additional N fertilizer can be applied at the beginning of reproductive growth between panicle initiation and panicle differentiation (2-millimeter panicle).

Water-seeding has been used in the past for weed control. Will water-seeding make a comeback to help with weedy rice suppression (or possibly for organic rice producers)?”

Dr. Levy’s discussion describes how water-seeding can help suppress weedy rice while presenting challenges for stand establishment. Another approach, developed through decades of organic rice production in California, demonstrates how carefully timed flooding and drainage can help manage different weed populations.

Learning from Lundberg Family Farms: Using Water to Control Weeds in Organic Rice

One of the most interesting examples of water management for organic rice production comes from Lundberg Family Farms in Richvale, California. In a recent article published by Rice Farming², the Lundberg family’s approach to using flooding and drainage for organic weed management was described in detail. The Lundberg family began growing organic rice in 1969 and has spent decades developing production practices that rely on water management rather than conventional herbicides for weed control.

Their experience provides some useful lessons for our Texas organic rice producers.

The Lundbergs have learned that water depth and timing can make an enormous difference in controlling weeds. By maintaining relatively deep floodwater during early rice development, they can suppress certain grass weeds while allowing the rice crop to continue growing. Once those weeds have been suppressed, they drain their fields to create conditions unfavorable for aquatic weeds that thrive in standing water.

Flooding suppresses some weeds, while draining can suppress others. The challenge is knowing when to change water levels without injuring the rice.

Aerial view of rice fields in California’s Sacramento Valley. Photo credit: Lundberg Family Farms.³

Making this system work requires precisely leveled fields, reliable irrigation and drainage systems, vigorous rice seedlings, and careful observation of weed and crop development. It also requires an understanding of the weeds present because not all weeds respond to flooding in the same way.

What Does This Mean for Texas Organic Rice?

Our organic rice growers face some serious weed challenges, particularly weedy rice, grasses, hemp sesbania, and jointvetch. Water-seeding and flood management offer opportunities to suppress some of these weeds, but no single water management practice will control all of them.

I believe the most important lesson from Lundberg Family Farms is that we should consider water management as part of a complete organic weed control program rather than simply as irrigation. Variety selection, seedling vigor, field preparation, leveling, fertility, and water management all work together.

I also believe there are opportunities for additional research in Texas to evaluate water-seeding methods, rice varieties, and flood management strategies under our growing conditions.

The experience I had visiting Joe Broussard’s farm near Nome several years ago demonstrated that water-seeding can make a tremendous difference in weed management. The Lundberg family’s experience reinforces what I saw in that field.

Further Reading: How Is Rice Grown at Lundberg Family Farms? — Rice Farming, October 29, 2026

A Challenge with Water-Seeding: Rice Seed Midges

Although water-seeding offers important opportunities for weed suppression, it also creates conditions favorable for certain aquatic insects. Rice seed midges are one example, particularly during the vulnerable period between germination and early seedling establishment.

Rice Seed Midges – The larvae of these insects (Order Diptera, Family Chironomidae, Genera Tanytarsus and Chironomus) are aquatic and can be very abundant in rice fields. The adults are small, gnat-like flies that typically form inverted pyramidal mating swarms in the spring over stagnant or slow-moving water. Female flies lay eggs in ribbons on the water surface. The larvae hatch and move downward to the flooded substrate where they build protective “tubes” of silk, detritus, and mud. These brown; wavy “tubes” are easily observed on the mud surface of rice paddies. Occasionally, the larvae will exit the tubes and swim to the surface in a whiplike fashion, similar to that of mosquito larvae. Midge larvae can damage water-seeded (pinpoint or continuous flood) rice by feeding on the sprouts of submerged germinating rice seeds. Damage can retard seedling growth or kill seedlings; however, the window of vulnerability to midge attack is rather narrow (from seeding to when seedlings are about 3 inches long).

Control rice seed midge problems by dry seeding, then employing a delayed flood, or by draining water-seeded paddies soon after planting. Thus, a pinpoint flood should reduce the potential for rice seed midge damage relative to a continuous flood. For water-seeded rice, reduce rice seed midge problems by increasing the seeding rate and planting sprouted seed immediately after flooding.

The following California research article evaluates several treatments for rice seed midge management. Organic rice producers should verify the current registration and organic production status of any material before considering its use.

Management of Rice Seed Midge – Insecticide Trial Results

References

1. Levy, R. (2022). The Art of Irrigation Begins Now. Rice Farming, April 2022. See section titled “Water-seeded rice.” ↩︎
2. Rance, H. (2026). How Is Rice Grown at Lundberg Family Farms?. Rice Farming, October 29, 2026. ↩︎
3. Lundberg Family Farms. Our Story. Company history and organic rice production practices. ↩︎