Hi, several leaves on my Japanese Maple Higasayama have turned brown and are falling off. Most of the Japanese Maples leaves look fine though. This happened after we hit 90 degrees 2 days in a row. The tree gets a nice amount of morning and afternoon sun but it also gets some shade from tree's overhead. We've had a wet spring but now the ground seems slightly dry. Should I be concerned? The tree's on it's 2nd year in the ground and the leaves scorched last year too around the summertime. Does this tree normally burn in too much sun in hot weather? Thanks
I have a Higasayama that is older and much larger than yours. It is in full sun and does not get scorched. I don't see anything in your pix that would cause me any concern. The few brown leaves look like normal leaf drop caused by insufficient sunlight (this sort of thing happens frequently with a. plamatum bonsai - shaded leaves turn yellowish, then brown and drop). If this becomes a problem in the future, I suggest finding a way to get it more sun exposure.
Thanks for the help. Many more leaves are falling off the tree. We hit 90 degrees for 2 days and the soil almost dried out, could that be why it's stressed?
Quite possibly. When I first saw my tree in its 20-gallon-ish nursery pot it had 'flamed out' - all the leaves were crispy brown. The nurseryman told us that 'the sometimes do that, it will leaf out again' and indeed it did. It has now been about 10 years in my yard and has never done it again. It is situated in well-draining, irrigated a garden bed. It rarely gets to 90F here, but we did have a week of 100+ highs a few years ago. Given these things, my guess is that soil dryness is the most likely source of your problem. 90F might be stalling growth, but nothing more, IMHO. Optimum root growth temperatures are around 70F. Root temperatures can soar in pots when the soil dries - likewise for earth. Yadda, yadda, yadda, obviously I am theorizing. Try more water and patience. This is my best guess.
I like @osoyoung 's guess, but be careful, because when leaves are dropping too much water looks just like too little. So if you're already watering...
Yes. We have long stretches of 90's during the summer. We have a very old Higasayama that we purchased 7 years ago and planted it in the ground in part sun. (It spent most of it's life container grown at a local grower as their stock plant for grafting for 30+ years.) The first few seasons we would get the problem that you describe and show in the photos when we hit the heat of Summer, which now seems to come in June. This variety will need water in the heat and does not like to dry out. Adding only water helped a little to sustain the tree, but it was always an uphill battle in the heat. The game changer was using a high quality organic fertilizer. The biggest change for us was using a high quality organic fertilizer with microbes and beneficial rhizosphere bacteria to assist in mineral release and promote soil fertility. This stopped the problem of yellow/Browning leaves and really improved the health of the tree. This problem is usually a result of a potassium deficiency due to the lack of water, too much water, or a lack of potassium in the soil. Using a high quality organic fertilizer as mentioned will add potassium, but more importantly will improve the roots ability to take up water and nutrients including potassium. The tree will establish much quicker, be more tolerant to drought, heat, and will be healthier too. My tree gets much more shade than your tree so lack of lighting is not the issue. The problem you describe can be a lighting issue in many varieties, such as mikawa yatsubusa for example. I thought it was the case for Higasayama too, until the issue was fixed with organic fertilizer with beneficial microbes and bacteria. Now my Higasayama gets a little more shade and does not have any problems with the heat or leaf loss. I recommend that you invest in a high quality organic fertilizer with mycorrhizae and beneficial bacteria. I use PHC Roots 7-7-7 on a regular basis for all landscape and container grown maples including those grown as bonsai. We also use their PHC 3-4-4 azalea blend on maples, evergreens, and rhododendrons. You may consider the M Roots 3-3-3 instead. Am Leonard offers all 3 to choose from or the product info and labels so you can see the ingredients. If you prefer to buy it locally but can't find, then maybe you can find a comparable product with similar ingredients. A.M. Leonard Tools for the Horticultural Industry since 1885.
A few tips if you decide to fertilize. Do not use chemical fertilizers because they can kill a stressed tree. Chemical forms of nitrogen like urea will fuel growth of harmful bacterial pathogens like pseudomonas, which Japanese maples are highly susceptible. A dedicated mycorrhizae product needs to have sea kelp or seaweed meal to feed and establish mycorrhizae in the root zone to get positive results. A study indicates using straight mycorrhizae provides no benefit to the tree. Article Request Page The study was on mulch depth and the impact of mycorrhizae and the benefits of adding sea kelp was an unintentional finding. I found all the benefits of roots without having to buy a 40lb bag. More cost effective for those who want all the benefits of microbes in a 3oz pouch (note this has kelp meal too) sold on Amazon Amazon.com : Roots 2756569 Tree Saver Fertilizer, 3-Ounce : Fertilizers : Patio, Lawn & Garden Here is the detailed information from the manufacturer. ROOTS Tree Saver | LebanonTurf.com Remember Japanese maples, in their native habitat, were grown in ancient forests as understory trees. Adding the beneficial microbes found in these established forests has made a profound impact on my Japanese maples (landscape grown, container grown, and bonsai) and other landscape plants. It makes them much healthier, more intense with longer lasting colors, and more resistant to weather extremes. The benefits of mycorrhizae and beneficial microbes from Roots: ["The ROOTS® brand of biologically enhanced nutrients merge nature and technology to offer leading-edge solutions for turf and plant care. ROOTS products provide an all-in-one nutrient delivery system that feeds the plant while enhancing the biological life of the soil and plant ecosystem. Turf professionals, landscapers, growers, arborists, and nursery growers trust ROOTS to provide consistent color response, improved turf density and enhanced root mass. Some ROOTS products feature mycorrhizal fungi and naturally-occurring beneficial bacteria to restore to the soil what harsh management practices have removed. Our Technologies Mycorrhizal Fungi Mycorrhizal fungi expand the root zone and allow plants the ability to take in necessary water, nutrients and micronutrients that would otherwise not be available. Plant survival and performance can be improved by incorporating a diverse population of mycorrhizal fungi at planting and transplanting time. Several ROOTS products contain Myconate®, a proprietary, patented stimulant of VAM mycorrhizal fungi. No other mycorrhizal products contain this unique compound that stimulates both introduced and native mycorrhizal fungi to rapidly colonize plant roots. Beneficial Bacteria Forest soils are teeming with beneficial microbes, which contribute to the growth, health, and nutrition of forest plants. Unfortunately, many landscape soils often lack this biological diversity. Several ROOTS products deliver various species of beneficial bacteria selected for their ability to enhance soil fertility and plant nutrition, improve soil structure and, in some cases, protect from disease (i.e., EcoGuard). In natural forest soils and constructed landscapes, microbes are not just beneficial; they're essential to healthy plant growth. Biostimulants Sea plant extracts and meals are natural amendments for increasing the organic content of soil and improving overall stress tolerance. Seaweed products are completely biodegradable and provide an excellent nutrient source for beneficial rhizosphere bacteria to multiply and become established in the root zone. These natural products fit the "Naturally Better" philosophy of our ROOTS brand. Humic acids are powerful organic chelators that solubilize important minerals needed by plants. Humic acids help release bound mineral nutrients and hold them in soluble form where they are readily available for uptake by plant roots. Nutrient Delivery Systems Our biological technologies, combined with specialized plant nutrients, provide a highly effective nutrient delivery system for plant roots. Improved nutrient availability and distribution, especially during times of deficiency or stress, are important to a plant’s performance and health. Our naturally better products create sustainable landscapes that can cost less, provide more value, and last longer."]
