Hello there:   Yes, aphids are usually a sign of too much nitrogen, and 
also hot, humid conditions seem to bring them on.

Sprayers.  _SOLO_  makes what seems to be the most sturdy and 
user-friendly.  They clean up well, hold pressure, and definitely 
deliver a good, fine spray.  If you need a power model, check out True 
Value Hardware's model that mists.

Solo does make sprayers that carry other 'boutique' garden supplier's 
labels.  Best prices for them seem to be occasional sales from Peaceful 
Valley Farm Supply.  If you get one, be sure to keep vaseline or 
similar substance around to use around the gasket for the tank (the 
top, where you pump up the pressure)  It helps a great deal to have an 
even seal, if you apply some around the contact surface.

Ladybugs love aphids.  (I suppose you already know this, but they are 
handy to help out.)

We use our three Solo sprayers almost constantly, for Bt, fish and kelp 
mix with surfactant, and also a garlic oil and hot pepper wax mix that 
helps deter everything from deer to leaf rollers.

When changing formulas in the sprayer, be sure to clean the tip and 
hose thoroughly.  If you don't, the interaction of different sprays can 
sometimes lead to coagulated particles clogging up the nozzle.  Keep a 
spare nozzle around, in a clean, dry container, if possible.

Good luck.

-sue

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