During the early 1950s, the French seemed to be spreading many things, including insects, but there were no witnesses that could tie them to airplanes and they existed in Vietnam already, so it was hard to say if they were introduced. The only solid evidence was for Cladosporium, a genus of fungi that, the report argued, hadn’t existed in Vietnam before. It was unclear what were the effects, as Cladosporium didn't seem to harm humans, though it was noted that it could damage tomato plants.
The report of the third meeting of the Committee to Prevent Germs noted that at first farmers in the Red River Delta were worried but that there had been no effects since 1952, so they were no longer as concerned and were no longer paying attention. The committee posed the question:
Should the committee publicly denounce the plot of the enemy?
The committee recommended that the Việt Minh wait to make a denunciation until the agricultural and medical institutes could make further investigations.
The committee also developed several standardized forms that were supposed to provide a more rigorous report that could tie strange materials to enemy airplanes. These included the following short “Form A.” Longer forms were also developed that asked more specific questions about the airplanes, time and place of release, agricultural conditions, and potential effects. These more detailed forms also broke down observations according to vector, including insects and powders. Finally, these forms asked if the respondent was sure or not sure about what they had observed (NAV3 PTT ML2 2290).
Such forms aimed to establish the basic facts of biological weapons use. They also sought to determine credibility of the observer. Việt Minh leaders were convinced that the French were using biological weapons but having watched the international reaction to charges of biological warfare during the Korean War, they had some idea of the difficulty of convincing the international community that France, and its patron the United States, would employ such weapons. Scroll over the form to see a translation to English.