Module 1. Introduction to Rice as a Crop
It is certain that the domestication of rice ranks as one of the most important developments in history, for this grain has fed more people over a longer period of time than has any other crop. (Huke and Huke, 1990)
As this quote illustrates, rice is a particularly key crop for us humans. For example, Rice provides 25 to 85 percent of the calories in the daily diet of 2.7 billion Asians. This makes it the number one staple food crop on this planet. It is also worth noting that, unlike other major cultivated grains like wheat and maize (corn) which are also used for feeding livestock, rice is used mainly for human consumption.
As a cultivated crop rice can be considered a semiaquatic annual grass. In some part of the tropics it can also service as a perennial. It belongs to two species – O. sativa and O. glaberrima withO. sativa being the more widely utilized. There are as many as 120,000 varieties of cultivated rice.
There is really no need to present too much about rice on these course pages as there are several excellent Websites devoted to this topic. For those students interested in finding out more about this fascinating cereal crop you should visit and read the information contained on the sites listed below.
- Oryza sativa L. –http://www.hort.purdue.edu/newcrop/duke_energy/Oryza_sativa.html
- Oryza sativa Rice (grain) –http://www.fao.org/ag/aga/agap/frg/afris/Data/312.htm
- Rice in Latin America and the Caribbean – http://www.flar.org/
Lesson 1.2: Introduction to IPM in Rice
Before we start to go into details on rice IPM and the practices associated with this approach we would like to give you a short overview of how we view it. Perhaps the first and most important thing you should know is that rice IPM, particularly IPM for irrigated tropical rice, is somewhat different than for most other crops. Perhaps the most important of these differences is that insecticides are almost never necessary and their use should be avoided. As Mattheson (2000) says,
“Today’s view of the irrigated tropical rice ecosystem and corresponding recommendations for insect pest management, summarized by Way & Heong, represents a radical revision of previous ideas regarding losses to insect pests and the role of insecticides. Insecticide use is considered destructive under most circumstances, and not a fundamental component of rice IPM. Instead, successful IPM depends on farmers’ understanding of, and confidence in, resistance and tolerance to pests in a healthy crop protected by naturally occurring biological control. Action thresholds for insecticide use that are developed by researchers are irrelevant and should be discarded.”
- As this statement implies, a rice crop can tolerate most insect pests – if the crop is managed in such a way that ensures optimum health. A well-managed rice crop is grown in a very stable and resilient agroecosystem. The rice agroecosystem is characterized by a soil and aquatic foodweb that develops quite rapidly. One of the important results of this phenomenon is that it can support the development of beneficial predator and parasitoid insects even when their normal insect pest food source is not present. This means that there are usually plenty of beneficial natural enemies around to take care of even early-season pest migrants into the ecosystem. When insecticides are introduced into the rice agroecosystem this delicate balance is disrupted. This may result in such outcomes as pesticide resistance, pest resurgence, and pest replacement.
Of course, insects are not the only pests that can cause economic damage to a rice crop. We all know that weeds, diseases, snails, rats and birds can be equally or even more devastating. Although the rice ecosystem doesn’t have nearly the same innate ability to take care of these pests and may need help, their economic control is also dependent on sound crop management practices that can prevent or minimize damage.
The key message you should take from the above discussion is that crop and crop ecosystem management is the foundation of a successful IPM approach. This is summed up in what is often referred to as the first rule of IPM – Grow a healthy crop.
One important thing to know about IPM in general and rice IPM in particular is that different people and organizations have very different views about what it is and what practices should be included. Below are links to two articles, one from FAO and one from an advocacy organization of the American plant science industry. It would definitely be worth your while to take a look at these and see where their views are similar and where they disagree. If there is enough interest we could start a discussion board to discuss the contrasts. You will have an opportunity to suggest discussion topics later on in this module.
- Integrated pest management in rice –http://www.fao.org/DOCREP/005/Y6159T/y6159t02.htm
Lesson 1.3: Introduction to Rice Agroecology
IPM is a somewhat complex technology and knowledge of the ecological basis of the pest problem is essential in order to develop and implement tactics and programs that attempt to alter the crop environment to reduce pest problems. Understanding agroecology allows a practitioner to manipulate the numerous factors in an agroecosystem to make the environment unfavorable to pests while maintaining a favorable environment for the crop.
Lesson 1.4: The “Rules” of Rice IPM
In our Introduction to IPM lesson we talked about the first rule of IPM – Grow a healthy crop. There are, of course, some additional important rules that should be followed and various individuals and organizations have developed and are promoting their favorites. However, when it comes to rice IPM, we think that FAO’s Community IPM program has some of the most robust. Based on decades of research and over ten years of experience in Asia the members of this program have distilled 4 simple rules. In addition to rule one – Grow a healthy crop, they recommend that the rice IPM practitioner also:
2. Observe rice fields weekly.
3. Conserve natural enemies.
4. Recognize that farmers are IPM experts.
We agree that following these rules form the basis of a sound IPM approach but, for this course, we would like to make some slight modifications. First, we think that perhaps rule 3 is a bit too narrow and primarily focuses on insect pest management. While conserving natural enemies of insect pests is very important, we consider it just one of the various ways a grower can and should actively manage the rice agroecosystem to minimize pest damage from insects and the many other pests affecting rice including weeds, diseases and non-insect pests like snails, rats and birds. We have therefore broadened rule 3 to read – Actively manage the rice agroecosystem.
We would also like to modify rule 4 to make it more action oriented. While recognizing farmers as IPM experts is an important first step, we think that agricultural professionals can do much to empower farmers with the knowledge, information and skills they need to become effective IPM experts. Rule 4 for us thus becomes – Unlocking farmers’ IPM expertise.
We will be going into much more detail on each of these rules in the coming weeks and talk about ways to observe and promote the 4 rules, always keeping in mind individual grower circumstances and preferences. For now, we just want you to think about them and then go on to the next assignment. Just to review, the rice IPM rules this course is based are: