Preserve Selection and Design Considerations: Bassia is not yet considered a major problem and no management programs have been initiated. For this reason it is difficult to assess the recovery potential of areas where Bassia may occur.
Management Requirements: Weed control involves three fundamental objectives: prevention, eradication and control.
From a practical viewpoint, methods of weed management are commonly categorized under the following categories: physical, thermal, managerial, biological, and chemical (Watson 1977). Physical methods include both manual and mechanical methods. Thermal methods include both broadcast burning or spot treatment with a flame thrower. Managerial methods include the encouragement of competitive displacement by native plants and prescribed grazing. Biological control is usually interpreted as the introduction of insects or pathogens which are highly selective for a particular weed species. Chemical control includes both broadcast and spot application.
The most desirable approach is that of an integrated pest management plan. This involves the optimum use of all control strategies in attempts to control weeds. It is generally accepted as the most effective, economical and environmentally sound long- term pest control strategy (Watson 1977). The use of various control techniques should be compatible with each other. Broadcast herbicide application, for example, may not work well with certain managerial techniques (i.e., plant competition).
PHYSICAL CONTROL The physical control methods discussed below (manual and mechani- cal) produce slash debris that can be disposed of by several techniques. If the vegetation is cut before seeds are produced the debris may be piled and left for enhancement of wildlife habitat (i.e., cover for small mammals). Debris may be fed through a mechanical chipper and used as mulch during revegetation procedures. Care should be taken to prevent vegetative reproduction from cuttings. Burning the slash piles is also effective in disposing of cuttings.
MANUAL CONTROL Manual methods use hand labor to remove undesirable vegetation. These methods are highly selective and permit weeds to be removed without damage to surrounding native vegetation.
The Bradley Method is one sensible approach to manual control of weeds (Fuller and Barbe 1985). This method consists of hand weeding selected small areas of infestation in a specific sequence, starting with the best stands of native vegetation (those with the least extent of weed infestation) and working towards those stands with the worst weed infestation. Initially, weeds that occur singly or in small groups should be eliminated from the extreme edges of the infestation. The next areas to work on are those with a ratio of at least two natives to every weed. As the native plant stabilizes in each cleared area, work deeper into the center of the most dense weed patches. This method has great promise on nature reserves with low budgets and with sensitive plant populations. More detailed information is contained in Fuller and Barbe (1985).
Hand Pulling: Muenscher (1955) recommends hand weeding of Bassia, done most easily after a rain when the soil is loose. Plants should be pulled as soon as they are large enough to grasp but before they produce seed. The pieces of root remaining in the soil will not sprout again.
Hand Hoeing: Plants can be destroyed readily while they are still small by hand hoeing, either by cutting off their tops or by stirring the surface soil so as to expose the seedlings to the drying action of the sun. The object of hoeing is to cut off weeds without going too deeply into the ground and doing damage to the roots of desirable vegetation.
MECHANICAL CONTROL Mechanical methods use mechanized equipment to remove above ground vegetation. These methods are often non-selective in that all vegetation on a treated site is affected. Mechanical control is highly effective at controlling woody vegetation on gentle topography with few site obstacles such as rocks, stumps or logs. Most mechanical equipment is not safe to operate on slopes over 30 percent. It is also of limited use where soils are highly susceptible to compaction or erosion or where excessive soil moisture is present. Site obstacles such as rocks and logs also reduce efficiency.
Weeds may be trimmed back by tractor-mounted mowers on even ground or by scythes on rough or stony ground. Unwanted vegetation can be removed faster and more economically in these ways than by manual means and with less soil disturbance than with scarification. However, these methods are non-selective weed eradication techniques. They reduce the potential for biological control through plant competition and open up new niches for undesirable vegetation. In addition, wildlife forage is eliminated.
MANAGERIAL CONTROL Biological Competition: Sowing native plant species which have the potential to out-compete weedy exotics for important resources is usually a preventive method of weed control. In some cases later successional plants may be encourage to take root among the unwanted vegetation. Once established, natives may displace weeds by competing for water or nutrients or by shading out the lower growing plants.
Some plant species inhibit the establishment or growth of other plants through the effects of allelopathy (i.e., biochemical interference of one plant's growth by metabolic products produced by another plant). Native species with such properties may be propagated in treated areas to control Bassia but, as allelopathy is occasionally a trait of noxious weeds, it is wise not to replace an old problem species with a new one.
Prescribed grazing: Livestock readily graze on Bassia, although sheep have died after a single feeding (James et al. 1976). Goats have not yet been used to control Bassia.
BIOLOGICAL CONTROL The term "biological control" is used here to refer to the use of insects or pathogens to control weeds. The introduction of exotic natural enemies to control plants is a complex process and must be thoroughly researched before implementation to prevent biological disasters. Such tools are not normally suitable for preserve managers to implement.
The only mention of insect herbivory on Bassia in the available literature is of LYGUS leafhoppers feeding on the species in the late summer (Parker 1972). The degree to which LYGUS adversely affects the growth of Bassia was not reported.
Please notify the California Field Office of The Nature Conser- vancy of any field observations in which a native insect or pathogen is seen to have detrimental effects on Bassia. These reports will be used to update this Element Stewardship Abstract. Management techniques which may encourage the spread of species-specific herbivores may be desirable in controlling Bassia.
CHEMICAL CONTROL Detailed information on herbicides are available in such publica- tions as Weed Science Society of America (1983) or USDA (1984), and will not be covered comprehensively here. The Weed Science Society publication gives specific information on nomenclature, chemical and physical properties of the pure chemical, use recommendations and precautions, physiological and biochemical behavior, behavior in or on soils and toxological properties for several hundred chemicals.
Herbicides may be applied non-selectively (i.e., broadcast application) or selectively (i.e., spot treatments). Chemical control of Bassia has not been previously reported.
Management Programs: Contact: Ron Tiller, Preserve Manager. Kern River Preserve, PO Box 1662, Weldon, CA 93283. Tel: (619) 378-2531.
Monitoring Programs: No quantitative monitoring studies of Bassia were discovered in this research. Qualitative monitoring of control efforts is being conducted at the Kern River Preserve (Hewett 1985).
Contact: Ron Tiller, Preserve Manager. Kern River Preserve, PO Box 1662, Weldon, CA 93283. Tel: (619) 378-2531.
Management Research Needs: Monitoring is needed to determine whether Bassia is extending its range and whether it displaces native vegetation.
Biological Research Needs: How important is Bassia in displacing native plant species? Does Bassia grow in undisturbed areas? Does it only occur on alkaline soils? Does it have any noteworthy preferences or aversions with regard to its physical environment? What are distinguishing field marks of seedlings? Do individuals grow clumped or scattered? What is known of seed productivity, seed viability, means and rate of seed dispersal, as well as dormancy and germination?