The earliest angustifolia cultivars are showing some colour in the flower buds in Simcoe (Norfolk County) (Figure 1). Bloom will likely begin in about 2 weeks here. Bloom will be later than last year and probably closer to normal.
Figure 1. A ‘Thumbelina Leigh’ angustifolia plant in Simcoe on June 6, 2025, showing the first signs of colour on the flower bud clusters.
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Frost Damage
There have been a few reports of frost damage from this past weekend. In some cases, the developing bud has been killed, and in others, the whole shoot has wilted. If just the bud has been damaged, new shoots will emerge from the leaf axils. Some of these may still flower, but bloom would be highly variable (i.e., staggered over time) and much later than normal. If whole shoots have been killed, recovery will depend on the type of lavender. Angustifolia cultivars with this type of damage will develop new shoots along the woody stem and at the base of the plant. Lavandins with this type of damage do not recover as easily. If only the outer layer of leaves and shoots were killed, then the next layer would take over. If the damage penetrated through all of the green tissues, the plants may not recover. I have not received reports of this level of damage.
Regardless of the level of damage, there is not much that can be done to aid in the recovery. The plants just need time to send out new shoots.
Winter Damage
Many growers are reporting significant winter damage, especially on lavandins. By now, the ability of the plant to recover should be obvious (Figure 2). Plants with only one or two tufts of green on the sides and no other signs of green should probably be replaced, since full recovery is unlikely. Anything with more green may need some help to fully recover. By now, the thick canopy of dead leaves should be very brittle. Simply brushing the plants can knock off many of these leaves and allow more light to penetrate to the centre of the plant, where new shoots may be emerging. This can be done with a leaf rake.
Figure 2. A ‘Phenomenal’ lavandin plant with severe winter damage. Note the few small green shoots within the damaged portions of the canopy and a ring of green around the perimeter. This plant may recover if the new shoots within the canopy can be promoted by removing dead growth and pruning throughout the year to encourage branching.
Four-Lined Plant Bugs and Garden Fleahoppers
Four-lined plant bugs (FLPB) are active and in the later instar (development) nymphal stages in southern areas (Figure 3). Earlier instars would have fed at the very tips of new shoots, causing browning and twisting of leaves. The current stages and beyond will cause more distinct spotting on leaves and stems anywhere in the canopy (Figure 4). FLPB can cause extensive damage in lavender. Populations tend to build over several years. Often, growers have no issues for the first two or three years, minor issues for a few years, and then moderate to severe issues from then on. It is important to start suppressing populations before they get out of hand. Insecticidal soaps registered for aphid control on lavender may also suppress FLPB, but soon it will be too late to get good control of the insects for the year. Older nymphs and adults are likely less affected by insecticidal soaps.
Figure 3. A late-instar nymph of FLPB on a salvia plant at the Simcoe Research Station on June 6.
Figure 4. A FLPB nymph on a salvia plant, along with spotting of the leaves caused by its feeding.
Garden fleahoppers are probably the most damaging problem that most growers do not even know they have. They are tiny bugs, and their damage is not distinctive, which causes them to go unnoticed until damage is severe. They appear to be worse when lavender is grown on solid sheets of ground cloth compared to strips with grass between the rows. Often, their damage could be mistaken for nutritional problems, general poor growth, or disease.
Garden fleahopper adults are black and about 2 mm in length with prominent hind legs for jumping. Nymphs, which have just started to emerge, are green and currently about 0.5 mm long. They suck juices out of leaves in protected parts of the canopy, causing a fine spotting/mottling of the older leaves. This can lead to yellowing of the leaves and defoliation over time. They have several generations per year, with populations building with each generation. Damage is worst in August, but management should begin much earlier if scouting indicates an increase in populations. While there are no thresholds for knowing exactly when sprays may be warranted, populations of 50-100 per mature plant or more may necessitate control based on previous experience. To estimate populations, place a white sheet of paper under the side of a plant and shake the plant vigorously. Quickly count the total number of nymphs and adults on the sheet of paper (before they jump off again). Estimate the number of sheets of paper that would have been required to surround the plant and multiply your count by that number.
The same insecticidal soaps that can suppress FLPB will likely also suppress garden fleahoppers. Conventional products that provide full control may be an option if the lavender is only grown for ornamental purposes (i.e., no culinary uses). Contact me if you want to explore those options.
In previous years in Simcoe, populations of garden fleahopper have likely topped 1,000 insects per plant in every plant (angustifolia and lavandin) in the experimental plot (around 400 plants). The damage was so severe that virtually every leaf fell off the plant except for the newest growth at the tips of the shoots. Conventional insecticide sprays were required to get the populations under control. As a result, it is very important to monitor populations throughout the year. For more information on FLPB and garden fleahoppers, including photos of different growth stages, biology, scouting information, and cultural management, visit Ontario Crop IPM. For the products registered for use on lavender as a culinary herb, visit the Ontario Crop Protection Hub. While there is nothing registered for management of either of these two pests in lavender, insecticidal soaps applied for aphid control (active ingredient = potassium salts of fatty acids) may also suppress populations of these insects.
