Here is a message and 2 photos from a friend who wonders what is damaging some of the leaves on her young Japanese maple. Do you think this is an insect problem or just cultural damage? "Leaves at the ends of branches look “chewed”. At first I thought they had been battered by the recent high winds, being only the newest leaves at the ends. Now I’m wondering if an insect is involved. Otherwise, there’s new growth coming along."
Hi Margot, we have exactly the same on our Palmatum Atropurpureum. This occured a few days after we had some strong wind in Spring when new leaves were forming. We check our plants regularly for insects especially in the Spring around new shoots and we had nothing. Over the past 40 years of collecting we have always found the reds are susceptible to wind damage to the tips from either strong winds or a late frost. So I would suggest if she has had no late frosts, your friends Maple has suffered wind damage and not insect attack. Hope this is of help.
The pot may benefit from a stand. The micro climate that close to a hot drying surface can cause damage to the leaves. It would be like trying to grow a Japanese maple in the open desert. Also when gusts of wind hit they maybe strong enough for leaf tips on lower branches to get damaged by the hard rough surface below. Also what may contribute is if they are using tap water. Chlorine or most likely chloramine does not off gas like the old chlorine that was used in tap water. I have found young and newly planted maples are most vulnerable. Especially when watered overhead and droplets are left on the leaves. Rain water is best, next option would be a charcoal filter. Avoid spraying the leaves by watering close to the pot surface. Lastly remove the dish. Japanese maples hate wet feet. The lower area of soil stays too wet and can cause leaf damage (early warning sign) that in time will result in root rot, then death. The soil in the lower third will become like a swamp which is a breading ground for soil born pathogens. It also limits the soils ability to drain, limits oxygen, which in turn reduces the maples ability to take up water which leads to dry spots of the leaves. The spots are due to the inability to keep up with transpiration on those windy days or hot sunny days.
