Hello Victoria,

If the only symptom on the rose so far is the blackened flower buds, then neither rust nor black spot are suspect, although both can be common rose diseases in general, at least on susceptible varieties. Fortunately, rust and black spot, both leaf infections when on roses, are fairly aptly named: rust fungi produce bright yellow-orange or rusty-orange spores, whereas black spot produces blackish lesions on the leaves. (The edges of the spots are more feathery and diffuse in black spot than with other common leaf spot fungi on roses.)

Trimming off the bad flowers is the best first step. "Blasted" flowers, which are those buds that die before opening, could have been damaged by thrips feeding or the larva of a fly called Rose Midge.

All four of these conditions are included in our rose diagnostic page if you'd like to learn more. While fungicides can sometimes be effective at preventing new infections if regularly applied, they cannot cure existing disease, and as you noted, their use may put pollinators or other organisms at risk, so we discourage their use.

Yes, you can remove heavily-infected foliage and dispose of it (don't compost). While this isn't foolproof for eradicating a disease, it can help to reduce how many spores stick around to cause new infections. This winter, remove all dead rose debris (canes with dieback, fallen leaves, frost-killed flowers) to help clean-up the area and further reduce the likelihood of overwintering spores.

Neem oil can sometimes be a useful insecticide for certain pests, like aphids or roseslug sawfly larvae chewing holes in the leaves, but the spray must contact the pest directly to be effective; its dried residues don't have any benefit. It's also a better insecticide than it is a fungicide, and treatments of neem oil won't really prevent many diseases. Horticultural oils in general, which include neem as one type, are considered quite low-toxicity on the spectrum of pesticides, in part because their residues are not long-lasting. As noted on the linked page, they should not be applied while temperatures are above about 85 degrees, or plant tissue damage might occur.

Recurring fungal infections might weaken a rose over time, so depending on any other stress factors that might bother the rose and overlap, and without being able to see how vigorous or not it may currently look, it's hard to say if it would succumb to these problems. We'd guess not, and it will be fine, if an eyesore, and it stands the best chance at recover and tolerating minor stresses if it's growing in full sun (minimum 6 hours of direct sun in summer), with good soil drainage, occasional watering during drought, and (for non-climbing rose types) an annual pruning-back around February or so. Plant diseases can depend greatly on weather, being more prevalent in years with wet springs (or if plants are irrigated often by wetting the leaves), so an outbreak one year won't necessarily repeat itself to the same degree the next, which also gives a weakened plant some opportunity to recover.

Red Milkweed Beetles (the type most often seen on Common Milkweed, which we presume you are referring to) are native insects that rely on Milkweed as much as the Monarch butterflies do. We don't encourage their removal, because an established clump of Milkweed should tolerate any damage from the beetles with little decline, but yes, you can knock them off or knock them into soapy water if want to get rid of them for the time being. (Other beetle adults could always fly into the area and re-colonize the plant later, so it's not a permanent solution.)

Miri

On 06/11/2024 3:58 PM EDT Ask Extension <<personal data hidden>> wrote:

 

 

You're welcome!