Boxwood

Question: We have 5 large boxwoods that have some sort of disease.  We will be removing the boxwoods.  Do we need to remove the soil in that area before planting new bushes?  If so should we also treat the area with anything?  Thank you

responder: An Ask Extension Expert Replied September 09, 2024, 1:55 PM EDT
response: These appear to be euonymus afflicted with euonymus scale--insected thgat are armored and feed on plant sap.  Scale insects don't infest the soil. There may be some lingering around after their host plant is removed if knocked off, but they will eventually die without the type of plant they are associated with. So, if you immediately planted with more euonymus or boxwood, holly,  lilacs, pachysandra ground cover, English ivy or honeysuckle--then you'd have a problem since this particular scale insect would feed on those and increase its numbers on the plant.  If you aren't planting those things, you would be safe to just amend and plant in that area.

responder: The Question Asker Replied September 09, 2024, 9:20 PM EDT
response: Thank you for your reply. That is helpful information.  How long would we need to wait to plant boxwoods in that area again?   On Sep 9, 2024, at 1:55 PM, Ask Extension wrote:﻿

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied September 10, 2024, 3:05 PM EDT
response: Euonymus Scale have two generations per year, so at most, a few months should be all that's needed to have no host plant available for the scale to recolonize. Even so, this is probably not necessary, and scale could always blow-in (or arrive through other means, like hitching a ride on bird or squirrel feet) at any time from an infested plant some distance away (say, elsewhere in the neighborhood). Therefore, you can replant whenever you're ready, since as Sue mentioned, it's highly unlikely any scale will remain behind after plant removal that are capable of moving onto a new plant. (After settling-down on the plant to feed, armored scale don't really move again under their own power, since they are functionally legless at that point. If they get rubbed off, their mouthparts are probably still embedded in the plant, so they would not be able to feed again even if they were successfully moved onto a new plant, so they won't live long.)  If the area is suitable for boxwoods (aside from scale issues), you can plant now, since early autumn is a good time to plant shrubs. Avoid installing evergreens like boxwood and euonymus too late into autumn or else they may not establish enough roots before the soil surface freezes, which could cause more winter foliage damage or branch tip dieback. Boxwoods grow best in a mix of sun and shade; they will tolerate full sun, but it can stress them, and heavy shade also might result in sparser growth. Soil needs to drain well and not be compacted, since boxwood roots grow relatively shallowly and must have good soil oxygenation to thrive. Euonymus is more forgiving (though is often consumed by deer, if that's an issue) regarding its sunlight exposure and soil conditions, as long as it's not wet, though both plants will become more vulnerable to pest or disease issues if they are routinely sheared into dense shapes. Given that, select a variety whose mature size is roughly how large you want the plant to get without relying on pruning to maintain size.  Miri