String formula for linear models - r

Question

I'm trying to create a string formula with the independent variables that are significant within my linear model, though I'm finding it difficult trying to include the + at the end of each variable.
I have tried:
as.formula(sprintf("encounter ~ %s",
names(tbest$model)[-1]))
However, this only gives the first variable:
encounter ~ open_shrubland
Warning message:
Using formula(x) is deprecated when x is a character vector of length > 1.
Consider formula(paste(x, collapse = " ")) instead.
How would I include all of them such that: encounter ~ X1 + X2 + X3 ..., also, can this be made functional, such that if I wanted to remove a variable, I would only have to do my.formula[-3] to remove it?
list of variable names:
c("open_shrubland", "Appalachian_Mountains", "Boreal_Hardwood_Transition",
"Central_Hardwoods", "Piedmont", "wetland", "Badlands_And_Prairies",
"Peninsular_Florida", "Central_Mixed_Grass_Prairie", "water",
"New_England_Mid_Atlantic_Coast", "grassland", "mixed_forest",
"cropland", "Oaks_And_Prairies", "Eastern_Tallgrass_Prairie",
"evergreen_needleleaf", "year", "pland_change", "evergreen_broadleaf",
"Southeastern_Coastal_Plain", "Prairie_Potholes", "Shortgrass_Prairie",
"urban", "Prairie_Hardwood_Transition", "Lower_Great_Lakes_St.Lawrence_Plain",
"mosaic", "Mississippi_Alluvial_Valley", "deciduous_broadleaf",
"deciduous_needleleaf", "barren")

Answer 1

Using reformulate will be helpful.
reformulate(names(tbest$model)[-1], 'encounter')
If the list of variable names are in x :
reformulate(x, 'encounter')
encounter ~ open_shrubland + Appalachian_Mountains + Boreal_Hardwood_Transition +
Central_Hardwoods + Piedmont + wetland + Badlands_And_Prairies +
Peninsular_Florida + Central_Mixed_Grass_Prairie + water +
New_England_Mid_Atlantic_Coast + grassland + mixed_forest +
cropland + Oaks_And_Prairies + Eastern_Tallgrass_Prairie +
evergreen_needleleaf + year + pland_change + evergreen_broadleaf +
Southeastern_Coastal_Plain + Prairie_Potholes + Shortgrass_Prairie +
urban + Prairie_Hardwood_Transition + Lower_Great_Lakes_St.Lawrence_Plain +
mosaic + Mississippi_Alluvial_Valley + deciduous_broadleaf +
deciduous_needleleaf + barren

Answer 2

We can create a formula with paste
as.formula(paste('encounter~', paste(names(tbtest$model)[-1], collapse = "+")))