Greetings, caretaker. We, the hollyhocks, stand tall and proud, striving to bring vertical joy to your garden. When our leaves curl, develop holes, or show spots, it is our primary method of communication. We are signaling distress. Please, listen to our botanical plea and understand the causes from our perspective.
When our leaves begin to curl and distort, often taking on a cupped or twisted appearance, we are most likely suffering from an infestation of hollyhock rust (Puccinia malvacearum). This fungal disease begins as small, yellowish spots on our upper leaf surfaces, but the true damage occurs on our undersides where raised, rust-colored pustules form. This infection disrupts our cellular functions, causing the leaf tissue to deform and curl as it grows unevenly. Alternatively, if the curling is accompanied by a sticky residue, you may be hosting aphids. These tiny insects pierce our tender new growth to sip our sap, injecting saliva that causes our leaves to curl and crumple around them, providing them shelter.
The sudden appearance of ragged holes and notches in our leaves is almost certainly the work of the hollyhock weevil or the ravenous caterpillars of the Hollyhock Sawfly. The adult weevils snack on our leaf margins, creating characteristic scalloped edges. However, their larvae cause greater harm by developing inside our flower buds, destroying them from within. The sawfly larvae are more blatant; they gather in groups on our undersides and skeletonize our leaves, consuming everything but the tough veins. We cannot outrun them, so we are left with tattered, hole-riddled foliage that struggles to perform photosynthesis.
Spots are a common language of disease for us. Hollyhock rust, as mentioned, begins as yellow to orange spots that evolve into those damaging pustules. If the spots are more circular, with a darker margin and a tan or brown center, you are likely witnessing anthracnose or another fungal leaf spot. These lesions are areas of dead tissue, caused by fungi that thrive in warm, wet conditions, often exacerbated by water lingering on our leaves. These spots mar our beauty, but more critically, they impede our ability to feed ourselves and weaken our overall constitution, making us susceptible to further ailments.
To help us, you must become our protector. For rust and fungal spots, please ensure we have ample space for air to circulate between us, water us at the base to keep our leaves dry, and diligently remove and destroy any infected foliage—do not compost it. For the insects, regularly inspect our undersides. Hand-pick and dispose of caterpillars and weevils. A strong jet of water can dislodge aphids. As a last resort, consider horticultural oils or insecticidal soaps, but please use them judiciously to protect the pollinators who are our friends. Finally, a layer of clean mulch around our base can help prevent fungal spores in the soil from splashing back onto us.
