Following the onset of an epidemic of foot and mouth disease (FMD) commencing in 1994 and affecting mainly pigs in the Philippines, a National Plan for the Control and Eradication of the disease was initiated. A disease surveillance buffer zone in the southern Luzon region of Bicol was established to protect the Visayas and Mindanao from infection and enable eventual elimination of the disease in Luzon. With achievement of Office International Epizooties (OIE)-certified FMD freedom with vaccination in the Philippines now imminent, the four components of the disease control strategy are reviewed, including quarantine and animal movement controls, strategic vaccination, surveillance and disease investigation, and enhanced public awareness with school on the air radio programmes. Although numbers of outbreaks declined following widespread vaccination, evaluation of serological responses in vaccinates suggested low levels of immune protection. The cessation of outbreaks was considered more likely a result of animal movement controls, improved surveillance and emergency response capability, and reduction in FMD-risk behaviours by livestock owners, particularly through efforts to enhance public awareness of biosecurity measures by the training of traders, livestock industry personnel and both commercial and smallholder farmers. A two-stage random sampling serosurveillance strategy enabled identification of residual infection that was not detected through opportunistic sampling and negative incident reporting. Intensive investigations of FMD outbreaks, particularly in Albay province in 1999, enabled improved understanding of the risk factors involved in disease transmission and implementation of appropriate interventions. The findings from this review are offered to assist development of FMD control and eradication programmes in other countries in south-east Asia that are now being encouraged to support the OIE goal of FMD freedom with vaccination by 2020.

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The feasibility of producing soil‐conditioning agents from agricultural residues by chemical modification was investigated. Such reactions as xanthation, cyanoethylation, methylation, hydroxyethylation, sulfation, phosphorylation, acetylation, and oxidation were applied to wheat straw, corn stover, corncobs, bagasse, rice hulls, and their major components. From results of comparative reactions on cellulose, hemicellulose, and lignin, the major part of the soil‐conditioning activity of chemically‐modified agricultural residues was found attributable to the substituted cellulose fraction. The extent of substitution required to produce active products varies with the nature of the derivative but coincides in all cases with that required to give water‐soluble products. Within these limits the degree of polymerization has more influence on aggregate‐stabilizing activities than either the type or extent of substitution. Data on a number of microbial gums, plant polysaccharides, and starch derivatives are also presented.

Agricultural residues, cotton linters, several of their chemical derivatives, and other related products were tested in the laboratory for their in‐soil stability against microbial degradation for a period of 6 months in a controlled humidity cabinet. A modified Yoder wet‐sieving technique was used to test the stabilizing effectiveness of a given polymer incorporated into Miami silt loam soil. Forty‐ to sixty‐mesh wheat straw, incorporated at a concentration of 0.5%, imparted greater stability to soil aggregates, following the first month of incubation at a temperature of 28° C., than did comparable applications of soybean and cotton stalks. Corn stover applications produced intermediate results. Twenty‐ to sixty‐mesh cotton linters at 0.5% concentration yielded increasingly effective soil aggregation during the first 3 months of incubation, reaching a maximum aggregation value of 93%. Chemically‐oxidized cellulose and corn starch showed surprising in‐soil stability throughout the 6‐month incubation period. In carboxymethyl cellulose samples, a degree of substitution (DS) of 0.7 or less was apparently insufficient to impart resistance to degradation by the microflora of the soil. However, carboxymethyl cellulose with a DS of 1.2 retained approximately 70% of its initial soilstabilizing activity over the 6‐month test period. In the case of hydroxyethyl and methyl cellulose, data are presented which tend to show that a high degree of substitution is not an adequate criterion of resistance to microbial degradation. Rather, the susceptibility of such polymers to enzymatic hydrolysis is apparently attributable to a lack of uniformity of substitution, resulting in a relative abundance of unsubstituted units in the cellulose chain.