Herbs - Not always pest free
Many people think of herbs as having no pests, and consequently pest management is often not considered an important aspect of herb production. Unfortunately, no crop is completely resistant to all pests, and over the past two years many pests have been observed attacking the culinary and medicinal herbs in the OMAFRA Herb Demonstration Garden. Of the 116 crops in the garden, more than 80 have had some form of insect or disease damage.
Japanese beetle feeding resulted in significant defoliation on basil, evening primrose, perilla and bloodwort (Figure 1). Mites did significant damage to numerous herbs (Figure 2), as did aphids and other sucking insects. The most common diseases observed in the plot so far are powdery mildew (Figure 3), downy mildew and Alternaria. A rust disease killed all the cinquefoil (Figure 4), and anthracnose killed much of the St. John's wort in the garden, as mentioned in a previous edition of Herb Blurbs.
Unfortunately, very few pest control products are registered on herbs in Canada, so herb growers must rely predominantly on cultural practices to manage pests. Scouting herb crops regularly for insects and diseases will help growers catch pest problems before they get out of hand, making management much easier.
Figure 1: Japanese beetles defoliating bloodwort
Figure 2: Mite damage to angelica
Figure 3: Powdery mildew on Virginia skullcap
Figure 4: Rust on cinquefoil
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