The first cultivars of Lavandula angustifolia are beginning to bloom in my research plots in Simcoe (Figure 1) and likely other farms in the southwest. ‘Big Time Blue’ was the first to bloom in my cultivar trial. Areas further north may be delayed a week or so. Early bloom is the time to harvest for bundles and buds so there are fewer dead and dried petals once they are dried.
Figure 1. The cultivar verification trial in Simcoe began blooming June 17.
Winter kill can often lead to variable bloom timing, which will make it much more difficult to time harvest for bundles and buds. If there are numerous under-developed shoots in the plant, it is probably best to wait until the buds on most of the shoots have fully developed. This will lead to more dead petals on more advanced flowers after drying but will avoid issues with variable bud size within the bundle and result in fewer losses of buds during bud cleaning. The only other option is to selectively harvest flowers, which will greatly increase labour requirements.
In my research plot, there are numerous plants that had developing flower buds suddenly stop growing and turn brown well before flowering (Figure 2). This issue appears to be cultivar-specific and unrelated to winter kill, since some plants that were mostly killed over winter do not show the issue while other plants with no winter kill are affected. Leaves are also turning a pale-green/yellowish colour in sections of the plant. It is unknown what is causing the issue, but root disease or a stem issue (e.g. different type of winter kill or a wilt pathogen) are the most likely culprits. It does not appear to be Phytophthora root rot, since sections of the plant are not dying completely. Samples have been sent for diagnosis. If you are experiencing these symptoms in your lavender, please let me know by emailing a photo or two along with the extent of the issue and cultivars affected to sean.westerveld@ontario.ca.
Figure 2. Flower buds not fully developing and turning brown as a result of an unknown disease or disorder.
This was a bad year for four-lined plant bug (FLPB). Adults are emerging now (Figure 3) and will feed for a couple more weeks before laying eggs and dying off. New growers may not see FLPB in the first couple years but then damage increases with age. Look for uniform-sized spotting on newer leaves and blocky, yellowish lesions on the stems. There is nothing that can be done at this stage to reduce damage. If you have an issue this year, the females will lay eggs in the lavender stems, which means that damage will also occur next spring. Insecticidal soaps registered for suppression of aphids in lavender, may also suppress young FLPB nymphs. Young nymphs usually appear in mid- to late-May each year.
Figure 3. Four lined plant bug adults on a mint leaf.
