By MaryAnne Musilo

Herb farmer Dan Mwangi saw his rosemary plantation wiped out by the soil fungus Fusarium Wilt, but with lime and soil testing his successfully rebuilt a rosemary business earning up to Sh300,000 a month from its exports.

Rosemary is widely cited as pest resistant, but its natural defences are against insects, rather than diseases.

“Rosemary does not require a lot of inputs in terms of pesticides. It is not affected by pests and diseases much compared to other herbs. This is because of its strong aroma that oils in the leaves and flowers that are sticky and tend to be unpleasant to insects. I decided to farm rosemary because when taken care of, it can serve one for at least 5 years because it is a perennial crop,” said Dan.

But Dan, who began farming in 2019 and is now growing rosemary across farms in Machakos, Ruai, Kajiado and Embu serves exporters selling to Europe and the Middle East and they prefer the taste of less pest-resistant varieties.

“I started farming herbs in 2019. I farm herbs like thyme, rosemary, basil, oregano and marjoram, but the most marketable and on demand ones are rosemary, basil and thyme, which are exported to Europe and the Middle East,” he said.

“I grow the rosemary Arp variety, which exporters prefer. This variety has a softer, sweeter and lemonier aroma than the other varieties that have a very strong aroma. This variety at times may be infested by pests if you compare it with other varieties that are pest resistant. Scouting for pests and weeding are crucial when it comes to rosemary plants. Pests like aphids come though they are rare, but caterpillars and spider mites are the most challenging when practicing rosemary. Diseases like Fusarium Wilt and root rot can also make a farmer make losses if plants are not taken care of,” he said.

Dan, himself, lost an acre of 8000 plants to Fusarium Wilt, which he puts down to poor soil care.

“It is important to do a soil test and have good drainage in the farm. This once made me get losses in an acre piece of land, due to Fusarium Wilt. I did not test the soil before planting. I can say it was out of negligence, a mistake not allowed in farming. The soil was acidic and the pH was below 6. So the same year we planted, I started to see the leaves yellowing and drying out.”

Once soil is infected with Fusarium Wilt, the fungus can almost never be cleared, but acidic soil conditions make it grow and attack plants much more vigorously.

“You know rosemary is woody plant, so the fungal infection restricts water flow in a way that is like severe drought, even if the surrounding soil is damp. We had to uproot everything because I knew it was the fusarium. Then I tested the soil and cubed the pH issue by adding lime to stabilise the soil and later replanted. I never made any cash from that farm that year,” he said.

“In cases where there are insect pests, I use neem oil, because in cases of exporting, the rosemary is not supposed to have chemicals. The neem oil disrupts the pests’ cycle. I spray on the leaves early in the morning and late in the evening, to avoid any reaction from the rosemary plant with the oils when it is hot or sunny, because it can cause burns,” he said.

With pests under control, Dan sells the herb at Sh300 per kilo making Sh15,000 to Sh75,000 a week. The amount is driven by demand. Harvesting rosemary can be done at almost any time, cutting as many branches as needed.

“I get my customers from international trade fairs and via social media. I got my first customer at the trade fair and he ordered many types of herbs, one of them being 200kg of rosemary. Today I also search clients through websites, like I have my own website and clients will always search for items or goods they want online and at times I get clients,” he said.

“Demand depends on how the market is, at times I can sell between 50 kg to 250kg a week. But putting it on a monthly basis, I roughly sell a tonne or more. The market is there. At times where there are festivals or Muslims holidays, I get a lot of orders because they use rosemary in cooking rice, meat and tea.”

The herb is also one of his most profitable, because it needs fewer inputs, last a long time and thrives in dryness and dry areas. Excessive water even harms the plant, causing root rot.

“Most places we plant in dry areas, because rosemary doesn’t like a lot of water. For example, the recent rains and floods in Ruai, caused a big portion of the plants to have root rot. Currently we are working on drainage. We will be raising the farm and digging trenches,” he said.