Wei Wei spent most of the day outside with the children catching ladybugs, and the harvest was quite bountiful.
Along the way, she also dug up some dandelions, cornflowers, and yarrows, planning to plant them next to the cornfield to provide a new home for these ladybugs.
The ladybugs, having been kept in jars for a while, were a bit listless, but fortunately, most of them were still alive. Wei Wei instructed the children to place the ladybugs on the leaves that were infested with pests.
Ladybugs move slowly, and after being placed on the leaves, they remain motionless for a while. It wasn't until some time later when they seemed to confirm there was no danger, that they began crawling toward the surviving aphids and started feeding.
As long as they started eating, everything was fine.
After finishing this task, Wei Wei, as usual, gave the children some food and then went back to her room to rest for a bit. Soon, it was almost dinner time.
During dinner, Wei Wei casually brought up the matter with Felix.
She was somewhat concerned about whether the wheat fields cultivated by the serfs on the estate might also be suffering from pests. After all, compared to the wheat seeds used by others, her wheat seeds had higher resistance to pests, yet they still got infected. Wei Wei wasn't sure if this was solely due to the other plants in the garden or if the wheat fields outside were also affected.
The land she cultivated in the garden totaled less than an acre, so even if there were some pests, they could be quickly dealt with. However, the situation outside was different.
"Garlic water can repel and kill some pests, but it's not a cure-all. It's best to prepare some pesticides."
Moreover, although garlic isn't as expensive as spices like Sichuan pepper or black pepper, it is still a seasoning. Producing large quantities of garlic water for pest control, which requires regular preparation, is something ordinary serfs can't afford.
Felix had been learning a lot about management recently and had a good understanding of farming matters. When Wei Wei mentioned aphids, he naturally thought of other common pests and diseases.
For farmers of this era, the appearance of pests in the fields usually meant they had to rely on manual removal. Often, before one field could be cleared, the neighboring fields would also become infested, leading to reduced yields or even complete crop failure. This was one of the most troublesome issues for farmers, aside from prolonged droughts or floods.
In fact, many fields suffered reduced yields due to pests every year. In an era without pesticides and relying solely on manual labor, serfs were quite limited in their ability to deal with pests.
So when Wei Wei brought it up, Felix also started to feel a headache coming on: "If it comes to that, I'll have people buy more garlic—but are you sure this method can kill pests?"
"Of course, at least it's very effective against small pests like aphids. You can try it yourself."
Felix's mind worked quickly. Trusting Wei Wei, he thought of other possibilities: "Is there any alternative? Something more affordable?"
If they could only use garlic, Felix would have to focus on his private fields. Other serfs would have to pay for the garlic themselves, and most of them likely couldn't afford it. In the end, they might have to increase their labor obligations to borrow some garlic from him.
But Felix felt that there wasn't much work requiring additional labor at the moment. Compared to that, he was more concerned about the cost.
This was probably the side effect of having been looking at accounts too much recently.
"An alternative?" Wei Wei was stunned for a moment, then suddenly realized something and couldn't help but slap her forehead: "There is! It's my fault for not thinking of it earlier. I'll go out and look for it tomorrow."
Previously, she had been limited by only thinking about what she had on hand, forgetting that there are many natural pest-repelling plants in nature.
For example, in ancient China, plants like Illicium and Tripterygium were used to make pesticides. Although there are no records of such practices in medieval Europe, in modern times, one plant is highly regarded for this purpose.
The next day, after watering the cornfield and wheat field with garlic water, Wei Wei went out alone with tools and on horseback to search for the plant she had read about in a book the previous night.
Although it took some time, she eventually found it.
Pyrethrum, a perennial herb native to Europe, belongs to the Asteraceae family. Its flowers resemble daisies, and it can be cultivated for medicinal purposes. However, in modern times, it is primarily used to make agricultural pesticides.
It is also the main raw material for mosquito coils.
Most plants in the Tanacetum genus of the Asteraceae family contain pyrethrins, which have a strong contact-killing effect on insects. They disrupt the normal physiology of insect nerves, causing them to become excited, convulse, and eventually die. However, as long as they are not used in large quantities, they are safe for humans and livestock. The downside is that they are highly toxic to fish and can harm some beneficial insects. Repeated use over time can also lead to pest resistance.
Of course, these drawbacks were not currently on Wei Wei's mind.
As a wild plant, pyrethrum is not rare. However, pyrethrum and daisies often grow together, and their flowers are very similar, making them hard to distinguish at a glance. Fortunately, although the flowers are similar, the stems and leaves are quite different, so paying attention to these details helps avoid confusion.
Both the flowers and leaves of pyrethrum can be used, and the roots can be left to regrow the following year. So after picking a basketful of flowers and leaves, Wei Wei also dug up a few plants to take back, leaving the rest to bear fruit or be harvested again next year.
This time, Wei Wei didn't take the pyrethrum to the kitchen for processing. Instead, she lit a fire in an open area outside the kitchen and set up a pot to boil the plants.
She boiled the flowers and leaves in a 1:10 ratio with water for twenty minutes. After boiling, she filtered out the plant material, leaving behind the pyrethrum water, which was the pesticide she needed.
Once cooled, the pyrethrum water could be used directly and would remain effective for up to two weeks. The only precaution was that the pots used to boil the pyrethrum water couldn't be used to cook other things during this period to avoid contamination.
Wei Wei had this batch of pyrethrum water sent to her fields for use. Earlier that day, she had gone out to inspect the fields and indeed found a few aphids. Fortunately, the diligent serfs had killed them, but it was still necessary to spray some pyrethrum water as a preventive measure.
The serfs trusted Wei Wei's instructions, especially after seeing the effects of burning manure. So the pyrethrum water she sent was quickly sprinkled across the fields, ensuring every wheat plant was protected.
Over the next few days, other wheat fields began to show signs of aphids and other pests, while Wei Wei's fields, which had been treated with pyrethrum water, remained completely pest-free. Even the fields adjacent to hers had far fewer pests compared to others.
Felix, who had been keeping an eye on Wei Wei's fields, naturally didn't miss this. Having already been convinced of Wei Wei's expertise in farming, Felix had sent people out to gather pyrethrum as soon as Wei Wei found it and made the pesticide.
After seeing the results, all the pyrethrum they collected was boiled into large quantities of pyrethrum water, which was then distributed to the earl's private fields for the serfs to spray.
Soon, other serfs noticed that this lightly scented water was very effective against pests in their fields. They approached the stewards, cautiously expressing their hope to buy some of this water from the earl—if the price was within their means.
This time, Felix ordered the method of making pyrethrum water to be kept secret—though it wasn't particularly difficult—and the serfs had to exchange a handful of beans for enough water to treat one field.
After all, he wasn't a philanthropist. Boiling pyrethrum required a lot of firewood, and giving it to the serfs for free was out of the question.
Exchanging a handful of beans for a pest-free field was quite a good deal, especially since beans were cheap. The serfs also discovered that diluting the "pesticide water" could treat two fields with almost the same effectiveness.
Although some people noticed that the castle's slaves were often seen wandering the fields looking for small white flowers, they vaguely heard that the women in the castle had recently been using a flower-based skincare product. So most assumed the slaves were picking flowers to make this skincare product.
Those who knew the secret kept their mouths shut, not only because of the earl's orders but also because the servants working in the castle could exchange pyrethrum for enough pesticide water to use on their fields.
With all this busy work, the pest problem that could have reduced the estate's yields was quietly resolved. The wheat fields remained lush and green, without a single pest in sight, a very pleasing sight.
The effectiveness of the pesticide water quickly spread beyond the estate through the serfs' word of mouth. Farmers in nearby villages and towns, already struggling with pests in their fields, heard the news and hurried to the estate with beans, hoping to buy some pesticide water.
Having nearly exhausted the pyrethrum within the estate, Felix, who had been discussing with Wei Wei whether they could clear some wasteland to grow flowers, heard the news and set the price for external sales at two handfuls of beans for enough pesticide water to treat one field. He also sent slaves outside the estate to search for more pyrethrum.
Originally, Felix had considered having the serfs exchange oats for the pesticide water, rather than the cheap beans that nobles rarely ate.
But Wei Wei's tofu made from beans had shown him that whether beans tasted good or not depended largely on how they were prepared.
Sardinson County, of course, did not have soybeans, which only appeared in Europe in the 18th century. However, tofu doesn't necessarily require soybeans to make.
The beans commonly eaten by European peasants at the time were peas and chickpeas, both of which could be used to make tofu, though they weren't as common as soybean tofu.
Bean products have always been a favorite food of humans. Wei Wei's decision to make tofu wasn't for the serfs' sake but rather a happy coincidence.
The reason was simply that she happened to be craving tofu.
Besides using brine or gypsum to coagulate tofu, white vinegar and lemon juice could also be used, though the texture would be slightly different.
While Felix was considering what to have the serfs exchange for the pesticide water, Wei Wei happened to grind chickpeas into soy milk and used lemon juice to coagulate the tofu for that night's tofu feast. During dinner, she casually mentioned that the kitchen's beans had all been used up, and Felix decided to use beans in exchange for the pesticide water.
This worked out well. The serfs, reluctant to part with other grains, didn't mind exchanging a handful or two of beans. Wei Wei soon had new beans to make tofu and develop new dishes, currently pondering whether she could find some brine or natural gypsum to improve the tofu's flavor. Meanwhile, Felix found new surprises on the dining table every day.