Pamela J. Bennett and Jane C. Martin
The winter of 1998 in Ohio was milder than normal due to El Niño. Temperatures were above average, and precipitation typically fell as rain rather than snow. Reports of winter-injured plants were essentially non-existent, and marginally hardy plants that are normally killed to the ground in winter (Buddleia, some hydrangeas, and more) were not damaged this winter. Spring was fairly typical across Ohio except for a wetter than normal April and June.
August and September were drier than normal in many parts of the state, and September was warmer than normal. This caused lawns to go dormant and trees and shrubs to show early signs of stress, such as wilting, early fall coloration, leaf scorch, and leaf drop.
This report includes a compilation of Ohio weather conditions and noteworthy environmentally induced and cultural plant problems in 1998. Observations were drawn from information provided in Ohio State University Extension's Buckeye Yard and Garden Line, the Ohio Department of Natural Resources Monthly Water Inventory Report, and information from the State Climatologist's Office for Ohio.
January and February in Ohio were warmer than normal. For example, temperatures in Columbus averaged 11.1°F above normal in January and 10.8°F above normal in February, while Cincinnati averaged 10.5°F above normal in January and 8.7°F above normal in February. During the January through March period, precipitation in Ohio fell as rain with little snowfall, due to the warmer than normal temperatures. Northeastern Ohio was the only part of the state that experienced near normal snowfall.
Temperatures in March and April were nearly normal, except for a few days of highs in the low 80s at the end of March. A few plants broke bud early and were later injured by low temperatures. Rainfall in April was above normal across Ohio, by an average of approximately 2.0". It was the seventh wettest April in Ohio in 116 years.
May brought above-normal temperatures across the state -- on average for the month, Cleveland was above normal by 6.4°F; Columbus above normal by 6.1°F; and Cincinnati was 3.7°F above normal. Rainfall was above normal in the southern half of the state and below normal in the northern half. Rainfall varied widely across Ohio with typical summer-like patterns of showers, heavy storms, high winds, and hail. The northern one-third of the state was very dry the last three weeks in May.
Temperatures in June were normal, though Columbus was slightly above average in June by 2.4°F. June was noticeably wet, and the rainfall average was 3.2" above normal, the second wettest June in 116 years. Rainfall occurred as light showers and intense downpours as part of dangerous storms and thunderstorms with several tornadoes reported. Floods occurred in the east-central and southeastern parts of the state. Precipitation for the first half of the 1998 calender year was above normal throughout the state, with the average being 5.0" above normal.
Temperatures in July were normal across the state. Rainfall for July was below normal for most of the state, averaging 87% of normal, or -0.5".
August temperatures were slightly above normal. Rainfall was above normal in the northern half of Ohio, but well below normal in the southern half. Monthly totals varied greatly across the state, from a low of 0.4" for the month in Westerville (Franklin County) to a high of 14.9" in Fostoria (Hancock County). Despite dry weather from mid August into early September, yearly rainfall totals (through September) were still above normal in several locations. Cincinnati was 11.0" above normal for the year, and the Wooster area was above normal by 5.5". Even though Columbus reported only 50% of normal rainfall for the July-September period, the area was at normal yearly rainfall totals.
September was warmer than normal and drier than normal across most of the state. Cleveland recorded average September temperatures as +3.1°F, Columbus was +6.1°F, and Cincinnati was +4.3°F. Rainfall was noticeably below normal. The state average was 1.3", which was 1.7" below normal for the month. This was the seventh driest September in the past 116 years.
Despite below-normal rainfall across Ohio in the late summer-early fall, precipitation for the 1998 calendar year was above normal at the end of September; the state average was 3.5" above normal. Lawns remained dormant in many areas, and deciduous trees and shrubs continued to wilt, scorch, and drop leaves earlier than usual.
Ohioans enjoyed a bounty of blooms in the spring despite a mid-March freeze. Crabapples at the Ohio Agricultural Research and Development Center's Secrest Arboretum in Wooster and other plants statewide bloomed about 10 days to two weeks earlier than the previous year. This phenomenon occurred throughout the spring and summer bloom period; sometimes blooming was noted two-and-one-half to three weeks earlier than occurred in 1997.
Several reports of a problem on pachysandra occurred early in the spring. Plants exhibited a marginal scorch symptom that in some cases encompassed a third to a half of the leaf. There were no symptoms of Volutella leaf and stem canker; it was thought to be related to winter dessication.
In most locations in Ohio, turf quality was poor by late June. Turf had gone from beautiful, lush, and green to ugly, stressed, and yellow-brown. Despite the fact that soil in many areas of the state was saturated, turfgrass showed heat stress quickly by late June. Roots had suffered in saturated soils in spring, fertilizers had worn off, and some turfgrasses experienced heavy seedhead formation; all of these factors contributed to poor quality. Also, from early August to mid September, dry conditions in many areas of the state led to lawns becoming dormant.
Numerous reports concerned a problem with river birches. In mid-summer, leaves yellowed and fell from the trees. Speculation was that the problem was not related to any disease, but to hot and dry weather that hit most parts of the state.
In dry weather, trees may lose up to 10% of the foliage to reduce water loss into the air; this amount of loss is not considered harmful to the plant. Also, inner leaves may be shaded out and are lost for lack of sunlight. Watering may serve to reduce stress but will not aid in recovery during the summer. If trees are fairly healthy, they will leaf out normally the following spring.
Numerous plants exhibited leaf yellowing and some leaf drop, especially of inner foliage, during the hot, dry spell in August. Plants experiencing this, in addition to the birches, were poplars, tuliptree, katsuratree, sweetgum, and many others. Early fall coloration was also evident on stressed burningbush and sourwood.
In the fall of 1997, a Plant Heat-Zone Map was released by the American Horticultural Society (AHS). The map was developed with the leadership of Dr. Marc Cathey. The heat zones are based on the average number of days per year that temperatures rise above 86°F. Eighty-six degrees was chosen because cellular proteins are damaged at temperatures above this.
The United States is divided into 12 zones. By using both rating systems, the AHS heat zones and the USDA hardiness zones, gardeners can select plants that are adapted to heat as well as cold.
Approximately 1,200 plants will be rated and eventually plant tags will have four numbers on them that indicate:
Despite recent research that has provided a greater understanding of tree root mor-phology, misconceptions remain and are being passed on to the public. In 1998, BYGL participants frequently discussed client questions concerning root problems and the confusion over the subject. The following information was provided in BYGL 98-23:
"Tree root systems resemble broad, shallow discs rather than tight, deep spheres. According to work done by Nina Bassuk (Cornell University), most of the root system is in the upper three feet of the soil, and about 80% of the feeder roots are in the upper six to eight inches of the soil. Also, more roots are found outside rather than inside the drip line. Many reasons have been given for this shape, but one of the most uncomplicated explanations has to do with oxygen. Tree root cells must absorb oxygen from the environment (the soil) since trees lack a cardiovascular system (heart, lungs, etc.) to pump oxygen to the roots. Put simply: deep soil = less oxygen = few roots; shallow soil = more oxygen = more roots.
"Statements that imply root growth is influenced by trees 'seeking' water, nutrients, or other resources falsely imply that trees can 'sense' such things -- as though they have a nervous system. The rate and direction of root growth is not influenced by a sentient ability for roots to pursue, search, or hunt for resources. Root growth is primarily controlled by the individual cells at the tips of the roots. If those cells acquire adequate resources from their surrounding environment (e.g., oxygen, water, nitrogen, etc.), they will grow. If resources are inadequate or conditions harsh, they will not grow. Root growth may follow a gradient, from a low concentration of resources to a high concentration, and this observation may insinuate that roots are 'seeking' those resources; however, it remains a simple matter of available resources: roots will grow where roots can grow."
1. The Ohio Department of Natural Resources Monthly Water Inventory Report is available at:
http://www.dnr.state.oh.us/odnr/water/pubs/newsltrs/mwirmain.html
2. Dr. Jeffrey Rogers, State Climatologist, with the State Climatologist's Office for Ohio, provides current and archived weather information for several locations in the state. This information is available at:
http://asp1.sbs.ohio-state.edu/climoff. htm