Today is the first recommended date of planting in SW Louisiana. I did hear of two producers who planted yesterday. After a cold wet winter, and sitting and trying to decide which Farm Bill option to select and with the depressed prices many producers are not really excited to get the growing season started.
Many producers are also still trying to decide what varieties to plant. With all the rain and cold weather, it looks like we will be off to a late start again this year. Many producers will try to wait as long as possible to be able to dry plant. Some will wait awhile and then decide to hold water and water plant.
Right now the problem with water planting is all the blackbirds, ducks and geese that are still around. With the decision on hold for AV-1011, many producers will not be able to water plant until most of the birds have migrated. The forecast calls for warmer and drier weather starting Friday. Let’s hope that it dries out and everyone can get into the fields.
Date of Planting:
As previously mentioned, today is the first recommended date of planting. Here is SW Louisiana the recommended dates of planting are from March 10 – April 15. Dr. Linscombe ‘s research has shown that the earlier you plant in the recommended time yields have increased. As Dr. Harrell stated in his field notes, at or below 50 degrees F rice seed germination is negligible.
From 50-55 F germination increases, but not to any great extent until temperature is above 60 F. Seedling survival is not satisfactory until the average daily temperature is above 65 F. The yield of many varieties will decrease significantly with later seeding dates.
Bacterial Panicle blight is associated with high day and night temperatures during pollination and grain fill. Later planted rice is more likely to encounter these high temperatures. Planting early also helps with some disease and insect pressure that may be greater later in the growing season. Also, if you plan to second crop the first crop should be harvested before mid-August. Planting by or before mid-April should allow for that harvest time.
Establishing a satisfactory stand is very important in a successful rice production system. Weather you intend to water plant, drill or dry broadcast the optimum stand is 10-15 plants per square foot. The minimum stand is 6-8 plants per square foot. Seeding rates for hybrids are much lower than inbred varieties.
Growers should consult the hybrid seed representative for guidelines and recommended seeding rates. Stands can be too thick as well as too thin. Really thick stands can lead to increased disease pressure as well as lodging.
Based on these recommendations: Planting on the basis of seeds per acre to obtain the desired plant population is more accurate than planting pounds per acre. For example, 90 lbs. of Bengal will contain fewer seeds than 90 lbs. of Cypress.
Under typical conditions, about one-half of the seed survive to produce a plant. The attached table showing seed per pound and seed per square foot should be helpful. With this in mind the recommended seeding rate for water seeding or dry broadcasting is about 80-120 lbs. per acre and for drill seeding about 50-80 lbs. per acre.
Some considerations include:
- Use higher rates when planting early into cool conditions
- Check (on the enclosed table) the number of seed per square foot at different seeding rates.
- With a blackbird, duck or goose problem use the higher rate.
- Where seedbed preparation is less than optimum use higher rates.
- Use higher rate for other conditions such as low seed germination, slow flushing ability or other similar problems.
- When water seeding, research has shown better stand are attained with pre-sprouted seeds as compared to non-sprouted seed.
Rice Water Weevil Management, with seed treatments:
Dermacor X-100, CruiserMaxx and NipsitInside are seed treatments that are applied by the seed dealer. Seed treated with Dermacor X-100 may be used in either dry or water seeding practices. CruiserMaxx & Nipsitinside, can only be used in rice that is drilled into a dry-seedbed. The main target of these insecticides is the rice water weevil. Aside from rice water weevils these seed treatments control different types of insects.
Dermacor X-100 will effectively control fall armyworms and will suppress injury from stem borers. Cruiser Maxx will control colaspis larvae and chinch bugs. If these seed treatments are used, there is little need to scout for rice water weevil adults because they are preventative treatments. However, there are some instances when adult rice water weevil feeding injury can be so severe that application of a pyrethroid is necessary to prevent dehydration and death of seedlings.
See the label for restrictions concerning crawfish production where any seed treatments are used. Data from small-plot research as well as some data from commercial trials indicate seeding at low rates (30 to 50 lbs seed per A) compromises the effectiveness of insecticidal seed treatments, particularly CruiserMaxx and NipsitInside.
If CruiserMaxx or NipsitInside are used in fields seeded at low rates, additional management practices should be considered, such as early planting or treating fields with pyrethroids or Belay if heavy infestations of RWW adults are found.
Information provided by: Dr. Michael Stout, Research & Extension Rice Entomologist; LSU AgCenter
Mold and Seedling Disease:
The following was written by Dr. Don Groth.
Water-mold or seed-rot disease complex is caused primarily by fungi-like Achlya spp., Pythium spp. The severity of this disease is more pronounced when water temperatures are low or unusually high. Water-mold can be observed through clear water as a ball of fungal strands surrounding seeds on the soil surface. After the seeding flood is removed, seeds on the soil surface are typically surrounded by a mass of fungal strands radiating out over the soil surface from the affected seeds. Temperatures averaging above 65 degrees favor seedling growth, and water-mold is less severe.
In the1970s and 1980s, an average of 45 percent of water-planted seeds were lost to water-mold. In addition to the direct cost of the lost seeds and the cost of replanting, water-mold also cause indirect losses through the reduced competitiveness of rice with weeds in sparse or irregular stands. If the weather is favorable for plant growth, seedlings often outgrow the disease and are not severely damaged. Seed with poor vigor will be damaged by water-mold fungi when water-seeded.
Plant when temperatures favor stand development. Seeds should have good vigor and have a high germination percentage. Treat seed with a recommended fungicide at the proper rate to reduce water-molds and seed diseases.
Seedling blight, or damping off, is a disease complex caused by several seed-borne and soilborne fungi, including species of Cochiobolus, Curvularia, Fusarium, Rhizoctonia and Sclerotium. Typically, the rice seedlings are weakened or killed by the fungi. Environmental conditions are important in disease development. Cold, wet weather is most favorable to disease development. Seedling blight causes stands of rice to be spotty, irregular and thin.
Fungi enter the young seedlings and either kill or injure them. Blighted seedlings that emerge from the soil die soon after emergence. Those that survive generally lack vigor, are yellow or pale green and do not compete well with healthy seedlings. Severity and incidence of seedling blight depend on three factors:
- percentage of the seed infested by seed-borne fungi
- soil temperature
- soil moisture content
Seedling blight is more severe on rice that has been seeded early when the soil is usually cold and damp. The disadvantages of early seeding can be partially overcome by seeding at a shallow depth. Conditions that tend to delay seedling emergence favor seedling blight. Some blight fungi that affect rice seedlings at the time of germination can be reduced by treating the seed with fungicides.
Seeds that carry blight fungi frequently have spotted or discolored hulls, but seed can be infected and still appear to be clean. Cochiobolus miyabeanus, one of the chief causes of seedling blight, is seed-borne. A seedling attacked by this fungus has dark areas on the basal parts of the first leaf. The soil-borne seedling blight fungus, Sclerotium rolfsii, kills or severely injures large numbers of rice seedlings after they emerge when the weather at emergence is humid and warm. A cottony white mold develops on the lower parts of affected plants. This type of blight can be controlled by flooding immediately.
Treatment of the seed with a fungicide is recommended to improve or ensure stands. Proper cultural methods for rice production, such as proper planting date or shallow seeding of early-planted rice, will reduce the damage from seedling blight fungi.
Water-borne and soil-borne fungi in the genus Pythium attack and kill seedlings from germination to about the three-leaf stage of growth. Infected roots are discolored brown or black, and the shoot suddenly dies and turns straw-colored. This disease is most common in water-seeded rice, and the injury is often more visible after the field is drained. It may also occur in drill-seeded rice during prolonged wet, rainy periods.
Rice varieties differ in their N requirements by location. Soil fertility, soil type, and other factors determine the efficiency of N utilization. Rice growers should determine the N rate that provides optimum grain yield on their land. Avoid N deficiency and excessive N fertilization. The following chart shows the general N recommendations for Rice Varieties.
Table 6. Nitrogen Recommendations for Rice Varieties
Varieties N rate (lbs/A)
Antonio, Caffey, Catahoula, Cheniere,
CL111, CL142, CL152, CL161, CL162, CL261,
CL271, Cocodrie, Colorado, Cypress, Della-2, 120-160
Jazzman, Jazzman-2, LaKast, Mermentau,
Neptune, Roy J, Taggart, Toro-2
CL151, Jupiter 90 – 130
The ‘right time’ to apply phosphorus
By: Dr. Dustin Harrell
The most efficient nutrient management decision can generally be made when you consider the “right source, right rate, right time and right place” for your particular cropping system.
So what is the “right time” to apply phosphorus (P) in a rice cropping system? How much yield do you lose when you delay P feritilizer? These are the types of questions that we have been trying to answer in our research program. The answer to the first is very easy and is the same for all crops, not just rice. Fertilizer P should be applied to the crop just before the crop needs it. This allows the crop to take it up before the nutrient gets “tie up” in the soil. The answer to the second question is not so straight forward.
A trial was recently conducted near Mamou, LA on the LaHaye farm in an effort to put numbers to the yield loss that would be associated with delayed fertilizer applications. The soil at the location was a silt loam soil with a pH of 6.2 and had a Mehlich-3 soil test P concentration that ranged from 2.4 to 7.4 throughout the field, which made it fall into the very low soil test P category.
In the trial, triple-super phosphate (TSP) was surface broadcast at a rate of 120 lb P2O5 per acre at one of five different times of application. Times of application included: at planting, preflood (four- to five-leaf rice), mid-tillering (two weeks after flooding), green ring and 50 percent heading. The yield results of the trial can be seen in Figure 1.
You can see from the figure that maximum yield occurred when P fertilization occurred at planting (8,608 lb/A) and the lowest yield occurred when no P was applied (5,585 lb/A). That accounts for a 54 percent yield reduction when P fertilization was not applied. A 12 percent yield loss was observed between the “at planting” and “preflood application” timings; however, this was not statistically significant.
Approximately 32 percent yield was lost when waiting until midtillering or green ring to apply P fertilizer. A yield loss of 52 percent was observed when P fertilization did not occur until 50 percent heading.
The bottom line is that P fertilizer in rice needs to be applied before tillering and flooding – the earlier the better. If P fertilizer cannot be applied just before or at planting, an alternative is to apply P around the 2-leaf state of development coinciding with the first Newpath application in Clearfield rice. If you are in a water-seeded system and scumming of the water is a problem, then a preplant incorporation of fertilizer is probably the best route to choose.
Rice Weed Control:
Weed control is critical for optimum rice production in both dry and water seeded systems. Early weed control increases yield. Timely applications are critical. In dry seeded production, four to six weeks may elapse between planting and permanent flood establishment and controlling weeds during this period is critical for maximizing yields. During this time weeds such as barnardgrass, boadleaf signalgrass, moningglory, and hemp sesbania can become established. Although these weeds can survive a permanent flood, establishment and maintenance of a sufficient flood over these weeds can enhance control.