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Eco-Audit Briefs General Site Conditions Hemlocks together with Rhododendron, Azaleas and Mountain-Laurel represents a natural mix of associated plants. In this garden, however, management in favor of the shrubs has diminished the Hemlocks. The Hemlocks in this mix have only modest growth and several specimens also show die back. Continuous battles with a variety of insect problems is a major force in the decline of these specimens. Close inspection of the Hemlock foliage reveals that different insects have had ascendancy at different times. Although, the latest waves of living Adelgid and Scale are within typical thresholds of survivability, the large populations of dead insects in these trees suggest quite a struggle has ensued to bring them under control. The excess use of nitrogen rich fertilizers for the Figure 1. Front gardens with shrubs is driving the population growth of the Adelgid and native mix of trees & shrubs making control treatments only marginally effective. Soil Conditions The soils in the front foundation have a good depth before there are significant restrictions to rooting. The imperfect drainage conditions in the bed are related to the poor development of the soil structure which limits effective percolation. There are beneficial levels of organic matter, which can help improve soil structure, but uneven mixing of this material across the landscape means the benefits will not be uniform. Soil chemistry shows a good balance of basic nutrients. However, the alkaline conditions in the bed (pH 7.5) will limit the availability of some nutrients and create an unfavorable soil environment for the plant material which tends to prefer more acidic conditions. The woody plants in this bed require a rich fungal soil biology in order to thrive. There are potentially good levels of fungal biomass, however, a lack of fungal food sources limits the amount of active fungal activity. In addition, poor drainage conditions are promoting bacterial growth and hindering development of more beneficial fungal activity. The uncomposted hardwood mulch used in the bed is forming fungal strands that glue the particles together and prevent proper movement of oxygen and water through the bed. Although this mulch can be a potential food source for beneficial fungi, its uncomposted character and the developing anaerobic conditions make it a liability. The mulch is also too high around the base of plants. Rising above the root crowns of the plants, it will cause longer term root development problems in plants. Recommendations The existing mulch should be worked into the bed with an air spade as a deep fungal food source, as a means to improve drainage conditions and to create more uniform distribution of organic matter . At the same time granular sulfur can be mixed deeply through the bed to alleviate the alkaline conditions. The addition of granular humates incorporated deeply into the bed would also improve the diversity of food sources to promote fungal activity.


Soils Analysis Results Parameter

Red Oak

Front Foundation

Roadside Bed

Lawn

Sandy Loam

Sandy Clay Loam

Clay Loam

Sandy Loam

Well

Imperfect

Imperfect

Well

4

4.5

Less than 1”

12 plus

24” plus

12” to 18”

18” to 24”

4 to 6

pH

5.6

7.5

7.1

6.7

Buffer pH

6.25

P (lbs/ac)

143

175

149

142

K (lbs/ac)

159

402

474

205

Ca (lbs/ac)

710

3305

3011

2448

Mg (lbs/ac)

137

Mg

335

274

CEC

11.5

10.7

9.5

7.5

K Base Sat (%)

1.8

4.8

6.4

3.5

Ca Base (%)

15

77

79

82

Mg Base (%)

5

18

15

15

7.9

10.1

5.3

Total Fungal Count (ug/g)

728

617

707

Active Fungal Count (ug/g)

15.8

1.54

9.05

Total Bacterial Count (ug/g)

612

677

703

Active Bacterial Count (ug/g)

43.2

24.7

38.6

Texture Drainage Percolation (in/hr) Depth to Compaction (in)

H Base (%)

78.3

Organic Matter (%)

4.9

Avg. Growth 2010 (in)

6.25

Avg. Growth 2009 (in)

10.25

Avg. Growth 2008 (in)

13

Recommendations Lime (lbs/M) K (lbs/M) Mg (lbs/M) Key Low Surplus

90 1


Irrigation The irrigation system is what has allowed the lawn to flourish in the absence of herbicides. It is also one of the limiting factors in building a truly sustainable system. The schedule is set to deliver daily brief waterings. This has led to excessive water use and shallow rooting in the lawn. This dependency would lead to severe problems for the landscape in a drought if a watering ban was declared. Water would have been wasted during rainy periods as the system also lacked a rain sensor. It is far more beneficial for plants to have a wet and dry cycle. Continuous high levels of water in the soil can inhibit many plants. The high level of watering likely also plays a role in the low CEC, as the soil biology that would improve this factor is limited by excessive moisture. A more reasoned approach would program the system to deliver deeper waterings at more infrequent periods. Recognition of seasonal patterns would also be of benefit to the landscape, with the cooler spring and autumn seasons requiring less supplemental watering. Recommended Wat ering Schedule

A Mon/ Thu

Spring B C Tue/ Wed/ Fri Sat

D

A Odd

30

Season Sum m er B C Ev en M/W Fri

D Ev en

A Mon Thu

30

Autum n B C Tue/ Wed/ Fri Sat

30 20 20

30

30

30 30

30 30

40 40 40 40 40 10

30 30 30 30 30 7

40 40 40 40 40 10

30

A B C D

30 30

30

3 .5

1 .5

30 30

30 30

1 .5

D Tue Fri

30 0.0

2 .6

1 .5

Prim arily lawn front of house Prim arily lawn rear of house, cy cle & soak Prim arily shrubs Shrubs, trees & v egetables below pool house

1 .5

0.7

3 .5

1 .5

0.5

1 .0


Cultural Measures Much more attention needs to be paid towards exposure of the root crowns of plants. There is mulch and earth climbing up the trunks of many plants. This leads to serious rooting and vascular problems that can dramatically reduce the vigor and lifespan of affected plants. Severe compaction problems in the lawn will need to be corrected by an air spade. However, annual maintenance of the lawn will require some measure of core aeration to reduce the impact of foot traffic and lawn mowers. When the cores are removed the property should be oversFigure 2. Buried root crown of Weeping seeded with new varieties of Rye and Fescue grasses that are resistant to common insect problems like grubs and Hemlock. chinch bugs. Once the lawn has about 50% of its area in these new varieties, these insects should not be a serious problem again. Fertilization & Sprays The all nutrient program for the lawn meets basic needs of the turf but fails to address the more limiting factors of the soil that could improve performance. A more tailored program could improve the availability of important nutrients and improve the character of the soil. This would include products that would improve soil biology as well as its nutrient status. A similar situation exists for the tree in the driveway circle where low levels of calcium would have limited the availability of fertilizers that did not first address this limiting factor. Low potassium and magnesium levels would also have limited plant performance. Improving the health of this tree, or subsequent plantings, should address these issues more precisely.

Figure 3. Over application of deer repellent on the Rhododendrons.

The insect spray program for the property includes a series of treatments that may not have fit in the mold of the more organic manner in which the lawn is managed. The annual use of systemic insecticide on the Birches targets an insect that is no longer a threat (Birch Leaf Miner); does not effectively treat the more catastrophic threats to the species (Bronze Birch Borer); and is now known to last upwards to a decade in a plant rather than the single year that was originally thought. The only truly potentially catastrophic insect problem in the landscape is the threat from Hemlock Wooly Adelgid and some of your Hemlocks are becoming too tall to treat with conventional oil sprays without significant drift going into your neighbor's property. A single systemic treatment may be all that is required for these trees for several years going forward.

The over application of the white fall deer repellent leaves the plants with a diminished photosynthetic capacity and makes a follow-up treatment in the spring redundant.

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