Peat-sand Mixture Research Articles

Effect of Mycorrhizal Fungi on the Growth and Nutrient Status of Slash and Radiata Pine Seedlings

SUMMARY Slash pine (Pinus elliottii var. elliottii Little and Dorman) and radiata pine (P. radiata D.Don) were inoculated with pure cultures of fungi isolated from mycorrhizas of mature pine. All eight species tested, except a Rhizopogon sp. obtained from slash pine, formed mycorrhizas with radiata pine, and all except two unidentified fungi from radiata produced mycorrhizas on slash. The effects of inoculation on yield and nutrient uptake were determined four months after seedlings were transplanted to a sterile peat-sand mixture previously steeped in nutrient solution. Inoculation gave better growth and improved nutrient status even where it did not result in mycorrhiza formation. Unidentified fungi were more effective than Rhizopogon roseolus or Suillus granulatus. Pine seedlings of any one species derived most benefit from inoculation with fungi isolated from that species. The results are discussed in relation to the problems of introducing pure cultures of mycorrhizal fungi into natural soils.

Propagation of Dieffenbachia

Sphagnum moss was a better potting medium than sand-peat mixtures. Single-node cuttings from the uppermost part of the stem, just below the leaves, produced larger plants than did cuttings from basal nodes. The height of plants 117 days after planting was directly proportional to the diameters and lengths of cuttings. The time required for emergence was also indirectly proportional to cutting length. Cuttings which were pressed into the potting media until their surfaces were barely visible produced larger plants than cuttings planted 3 inches deep.Dieffenbachia varieties responded similarly to the treatments, butD. amoena grew faster thanD. picta, D. picta ‘Exotica’ andD. picta ‘Rudolph Roehrs.’

Bioassay of Bacillus thuringiensis-Based Microbial Insecticides. III. Continuous Propagation of the Salt-Marsh Caterpillar, Estigmene acrea1

The salt-marsh caterpillar, Estigmene acrea (Drury), can be mass reared using alfalfa, Medicago sativa L., as caterpillar food for the first 7 days and primary leaves of the red kidney bean, Plzaseolus vulgaris var. rubra L., grown in sand-peat moss mixture, as food for remainder of the larval stage. Larvae are reared at about 26° C temperature for 7 days and then moved to a greenhouse with a diumal fluctuation of temperature (24–32° C) and RH (30–60%) for the remainder of the larval stage. A 16-hr photo period prevents larvae from going into a diapause. A period of darkness is necessary for good adult copulation and oviposition. Under these conditions, the requirement for the complete life cycle is 6 weeks. Sanitation measures illelude sterilization of egg chorion by a 1-hr soaking in 10% formalin, and dipping rearing cages and bean flats in 10% formalin after eaeh use. The methods described can produce 10,000 to 12,000 larvae per week.

VEGETATIVE PROPAGATION OF CONIFERS: IX. EFFECTS OF CHEMICAL TREATMENTS AND A WAX SPRAY ON THE OUTDOOR PROPAGATION OF SPRUCE CUTTINGS

Norway spruce cuttings were collected at intervals throughout the year, subjected to treatment with talc dusts containing from 5 up to 10,000 p.p.m. of indolylacetic acid, and propagated in outdoor frames. In some experiments, indolylacetic acid treatments were included in a series of dusts involving cane sugar, potassium acid phosphate, and organic mercurial disinfectants. Effects of wax coating of cuttings of Norway and white spruce and eastern white cedar were also considered.Indolylacetic acid treatment failed to have any general beneficial effects on rooting; concentrations of 8000 and 10,000 p.p.m. were usually injurious. However, treatment of apparently dormant cuttings, taken shortly before emergence of new growth, with 1000 p.p.m. gave 25% rooting, as compared to 8% for the controls, and tended to increase the length of root. Treatments with organic mercury, cane sugar, and potassium acid phosphate increased survival of new growth, and, in combination with indolylacetic acid, increased survival and root lengths.Talc treatment increased rooting to as much as 70% for cuttings planted in sand as compared to 25% for the controls, but had no effect on plantings in a sand–peat mixture. Talc effects were the most marked on cuttings taken before emergence of new growth and when planting was delayed for 24 hr. after treatment.Wax application had no effect on dormant spruce cuttings but was markedly injurious to summer collections. Injurious effects were reduced when wax was used in conjunction with indolylacetic acid treatment.