“Raindrops keep falling on my head.”
B.J. Thomas must have been talking about 2017 in that big hit. It just keeps falling.
The rain, itself, is certainly no problem and helping to keep pumping to a minimum. That’s one of the few blessings from the frequent heavy rains we’ve had all year.
However, the continued overcast conditions aren’t favorable to optimum rice production at this time. Cloudy weather reduces light penetration to rice leaves which can reduce yields if prolonged enough. The high humidity, long dew periods and frequent rains also make the year ripe for disease issues. We’ll see.
If you have heading rice, it’s also prime time for stink bug scouting. Several have reported fields at up to 5x threshold levels. It’s important to get good coverage with these applications to get optimum control – don’t short the water volume.
Rice Blast on the Go
Reports of blast incidence are still coming. So far (7/7), blast has been reported from Woodruff, Monroe, Perry, Pulaski, Lawrence, St. Francis and Clark Counties. Most finds have been on Jupiter but also on LaKast, Diamond, and Francis. Continue scouting!
Weather conditions for the past weeks appeared very favorable for blast disease. It looks like that weather; however, the disease may be slowed but not totally stopped. Blast severity levels depend on favorable environmental and weather conditions given compatible host-pathogen relationship.
Blast pathogen’s spores are airborne. Also, numerous studies have shown the survival capacity of the spores under wide ranges of temperature and relative humidity. It is wise to assume that the pathogen is somewhere around moving slowly or waiting for favorable conditions to reproduce on susceptible rice.
A number of studies and observations have shown that the life cycle of the blast pathogen goes in a series of overlapping cycles during the rice growing season – which means blast pathogen’s spores continue to be produced and infect the tender tissues of rice plants at any crop growth stage.
As a result, the leaves, collars, nodes, panicle branches and even seeds of a susceptible cultivar may get infected within a season.
Of all infections, neck (node) blast or neck rot is the most devastating and it can cause nearly 100 percent grain loss. So, be proactive and plan for protection using fungicides. Remember, the most common mistakes in rice blast disease management are:
- Planting susceptible cultivars in blast prone fields.
- Not scouting for leaf blast early in the season.
- Using inadequate water volumes for mixing and appliction.
- Waiting too long / late to make a fungicide application.
Two fungicide applications are recommended. The optimum timing for the first application to manage neck blast is when about 50% of the main tillers are at late boot to 10% heading and the second application from 50% to 70% heading but all necks still in the boot.
Leaf blast is often managed with a deep flood (greater than 4 inches). Fields that are more susceptible to blast are those that are difficult to hold a flood. Maintaining a deep flood of at least 4 inches after midseason can reduced the risk of blast and it may be worth at least one fungicide application. The optimal timing for only one application is at 30% to 50% head out of the boot.
For any fungicide application during heading to manage neck blast, the neck should still be in the boot. Trifloxystrobin (GEM 3.8 – 4.7 fl oz/acre) is considered slightly more effective on blast than azoxystrobin (Quadris 8.5 – 12.5 fl oz/acre). For adequate protection, full rates are preferred.
To read more on
- Blast disease, click here.
- Frequently asked questions about blast, click here.
- Fungicide timing for blast, go here.
Also, refer to MP154 for more information on fungicides and follow the fungicide labels – the label is the law.
Also On The Disease Front
Sheath blight: Temperature and humidity have started picking up in favor of sheath blight. Continue scouting! To read more on sheath blight here. To read more on fungicides go here.
Kernel smut: Warm and wet conditions also favor kernel smut. If your field has a history of kernel smut, the cultivar is susceptible, and nitrogen fertilizer rate beyond optimum then you need to apply the correct fungicide at the correct timinig. For this information read here.
To read more on fungicide rates and timing for major rice diseases read, go to: Rates and Contents of Fungicides; Fungicide Timings for Selected Rice Diseases.
Reminder: Arkansas Rice College is August 3
The 2017 Rice College will be held at the Rice Research & Extension Center at Stuttgart, AR on Thursday, Aug. 3. Register now on this page.
